How to immmigrate with green card into America

Immigration is a rather complicated process. While green card makes it easier for you, the overall process is not easy, although feasible.
In order to enter US border as an immigrant, you must obtain a visa. Visa is a legal document that certifies that you are authorized to enter United States for certain purpose. The green card visa is called Diversity Visa. If you win the green card lottery and pass the remaining checks, you will be able to obtain it. There are different types of visas, both immigrant and nonimmigrant. As an immigrant and a future american citizen, you will need the diversity visa - your immigrant permit.
The visas are issued by Immigration and Naturalization Service of United States. You can find out more about this government organization at their Internet web site. INS does not directly participate in green card lottery; winning the green card lottery simply means you are getting an opportunity to apply to INS for immigration on grounds of diversity immigration law.
There are permanent and temporary visas. Depending on purpose and expected extent of one's travel into United States, american laws specify which kind of visa should be granted to a foreign national. Notice that obtaining the green card visa does not make you a citizen of United States but a Legal Permanent Resident (which entitles you to all benefits of citizenship except for the right to vote). In order to become a citizen, you will have to wait for five years. During this period, your green card visa would serve you as a permanent permit to travel across US border. Nationals of certain "visa waiver" countries are entitled to enter United States border without need for a visa. They can simply present their passport.
It is very important to know that visas are applied for and issued through your consulate representative of United States. You can not obtain or require a visa when you are crossing the american border. Hence, you must obtain the visa before you actually enter the country.
You cannot apply for a visa when you arrive at a U.S. port of entry. Unless you're from a "Visa Waiver" country, you must obtain your visa at a U.S. consulate before you depart for the United States. If your plans change between the time you get a visa and the time you want to leave for the United States, you are required by law to go back to the consulate to obtain a new visa.
The application process for green card visa is not the same as the application process for green card lottery; it includes a lot of paperwork and interviews. US immigrations services will be verifying that you are not violating US immigration laws; for instance, that you are not a heinous criminal, a terrorist or otherwise unwanted by US officials. You will as well be interviewed at the border by the immigration inspector. You should abstain from lying or submitting incomplete information to any entity involved in your immigration application, as multiple mechanisms to prevent that are put in place by US immigration services and lying would put you in a very unfavourable light, up to the point of criminal prosecution or permanent loss of right of entry into United States.
As said above, you will most likely be questioned multiple times, at different stages of your immigration process and even after you receive your legal resident permit. Your bags might be searched. Do not by surprised or alarmed by it. Unfortunately, you are not allowed to have a lawyer represent you during your arrival or interrogations. If there are complications and you fail to provide clear and reasonable answers to the questions that the immigration services present, you might be sent into a specialized immigration court or deported back having your immigration permit cancelled. As long as you are careful with your paperwork, don't worry. There are always minor issues, they tend to happen, the immigration services are aware of it and they are considerate to it. The immigration regulations might seem too strict and even unfair to you, but they are necessary both for the security of United States and proper smooth operation of immigration services.
When you are questioned, your answers must be consistent, conscise, clear and in line with your previous answers. The authorities can ask you basically any question on the record. Answering questions dishonestly and untruthfully might cost you your green card.
Make sure that all papers you were required to have, as well as any additional documentation you believe might be helpful are valid, properly authorized and not outdated. Most importantly, make sure they are in place.
Be sure not to bring any potentially illegal or dangerous items or animals. Dress appropriately and behave politely and seriously.
Please understand that it is the nature of immigration officials to be suspicious and impatient. Immigration checks are the first line of defense of american liberty against external threats. Immigration officials aren't going to be friendly to you, but there's nothing personal in that; they get to handle thousands of people every month. The better prepared and calm you are, the less problems you're likely to run into.
The reason for such treatment and cautiousness is that the immigration authorities do not want to take a chance with anyone staying illegally. Unlike most other countries, United States doesn't have a single paper that unambigously identifies a person and must be carried at all times, such as ID or passport. Driver's licenses, foreign passports, resident permit green card and other papers can serve as a subtitute, but they aren't necessary for free movement in United States, so many illegal immigrants settle down. Incidentally, illegal immigrants are a major source of domestic crime in United states, and the immigration authorities are reluctant to allow anyone who might want to refuse leaving. Even though you are getting a green card, the immigration authorities will have to treat you with caution.