Let me add something to Bimala's answer. There are few states that allow you to take nclex directly with Nepal's RN certificate. Other states require you to take CGFNS exam first so look for the states that do not require cgnfs exam and make you eligible to sit for NCLEX exam with your Nepal's RN credential. I have some such states that do not require cgfns exam like New Mexico, Nevada, North Carolina, New York etc. There are more but I don't remember now. You can google for more information.