回複：我想自己申請美國綠卡，請各位牛人幫幫忙，那裏可以找到person

Go to www.uscis.gov to find which category your application will be suited and follow the directions for application for that application. For the statement, basically you have to ask for help from those whose applications are approved (friends, nice people in this forum. Basically copy and paste most of the context from your reference letters which are probably prepared by yourself but signed by professors or others). Therefore first of all, you decide the category, for example, EB1, EB2 subcategory NIW, and so on. In a word, your qualification determines your application.
Good luck.