If you are currently in the United States and you meet certain other requirements, you may file Form I-485, Application to Register Permanent Residence or Adjust Status to apply for a Green Card without leaving the country.
The Electronic Diversity Visa lottery is, as the name suggests, a lottery for Green Cards. There is no guarantee you will win, but if you have finished high school and have no other special circumstance that would allow you to obtain a Green Card, it may be an excellent option and at least worth the try.
