Alok, first go to the american embassy at the yak n yeti. Get the form filled out there so that you can marry a nepali citizen. After getting married , it takes 14 days to process and you can get the marriage certificate, which could get very long if you are not on top of it. Then, fill out the I-130 form. When you get the receipt number for the I-130, apply the I-129F to make the process faster. The whole thing takes about 6 months. hope that helps.