Do exactly what monkey said earlier. I have been through this but I did CP instead of AOS as my case number was high. So, print the forms of DS 230 from USCIS site, fill it out with true information and send it back along with the barcode KCC has mailed you in yellow (Brown) envelope. Then you also need to have 2*2 (2 by 2) photo from Walgreens or Wallmart and Paste it in the DS 230 form and send it to KCC. 

Furthermore, If your case number is low i.e., Below 20,000 then AOS will be better because you don't have to fly back to Nepal however you can always go for Cosular processing from Nepal. CP  is the easier process than AOS as CP needs very little documents.