I need more info on w7. How do I do it and what documents do I need.

Download W7 from Internal Revenue Service and read the instructions. If you have a specific question, then do ask it.
It appears that Nepal does not have any tax treaty with the U.S.

There is a passage from india to nepal through 2 highest mountains and the climate is different. Where is it?

This is a TAX forum; please stay on subject.