Use these measurements to calculate how much fabric you'll need. Get the fabric and preshrink it. Cut out your curtains according to your measurements, one piece per window. Measure and cut the tabs. Narrow-hem the tabs.
Machine hem the bottom of the curtains.
Bend the tabs over backward so that the fabric is wrong side in. Stitch by machine or hand. Visualize a castle. Tab-top curtains look just like the crenellations on a castle. Your goal is to create tabs that alternate with empty spaces of about equal width.