Dear Moazzam Husain,
You can download solar resource data for some locations in Pakistan from the source described in this post:
sam.nrel.gov/content/how-open-swera-tmy-file-within-sam
To use that data, you will need to convert it to the SAM CSV format. You should be able to use a spreadsheet program to copy and paste the relevant data from the original file to one in the SAM CSV format. Please see SAM's Help system for a description of the SAM CSV format, and the solar_resource folder of your SAM installation for examples of files that use the format.
Best regards,
Paul.