First you need to find the pattern pieces you need.
Open up your pant pattern and get the paper instructions out.
Find the sections that you see below in the photo.
I have high lighted the pants front and pants back I need number 9 and 10.
Look though the pattern paper and find your pieces the will be numbered.
Cut them out like the 2nd photo.
It doesn't have to be neat, I do a quick cut around the pattern to separate form the rest of the pattern paper.