Start off by stitching the pocket lining to the pants front panel along the curved edge.
Press your stitches and snip into the curve (but not your stitches!) so that the curve will lay flat. I also trimmed my seam allowance down to about 1/4". Press the seam allowance towards the lining and edgestitch the lining to the seam allowance. This helps the pocket lining from rolling out. Press flat.
Topstitch along the right side of your pocket's edge.
Take the pocket facing and place it right sides together along the pocket lining. Make sure the outer curves are lined up and that the top and side of the facings match up to the top and side of your pants front panel. Stitch together. Press. Finish the seam allowance which I haven't done quite yet.
This is what your front panel should look like now. I know it's a little hard to see with the polka dots.
Your next step will be to baste within your seam allowance along the top and side of where the pocket is. This helps prevent shifting when you go to sew the waistband and side seams.
Voila! An inset pocket!
My other change from the original pattern was to do a cuff hem. For that, I finished the hem's raw edge and turned the hem to the right side twice, 1" each time. Then I stitched in the ditch on the inseam and outseam so that the cuff won't come undone. I can't do it with this pair as it's printed and the wrong side is white. Wouldn't look quite as nice!