To make simple 'rod pocket' curtains measure the width and length of your fabric to fit your window.
Set up matching thread in the machine.
Then fold rough edges over measuring carefully so it's straight. Pin. I do the SIDES first folded a 1/2 inch. Pinned and sewn. Then the TOP where I fold 4 inches over and pin.
Here you can see I have already sewn the sides 1 inch folded over and sew on the 1/2 inch line. (Or fold it over twice so no frayed edges show).
Then I sew the top 'rod pocket' a 1/2 inch in from cut. Pulling pins out as I go. I repeat this step only I sew about 2 inches from folded edge to create top 'ruffle' about rod pocket.
Hang from rid pocket and re-measure hem. Pin. Measure from top to bottom FOLDS so the bottom is straight even if the cut is a little off.
Sew pinned hemline a little in from the cut about a 1/2 inch. Choose a measurement and be consistent so the bottom is straight.