Our curtains are 72 inches long so I needed a little more than double that amount in the length of my fabric cut- about five yards. Depending on how wide your window is you will need to get more than one cut of that length. Our window is a standard, single-window so I only needed one cut.
Once I got home I folded the fabric in half lengthwise and cut it into strips about 6-8 inches wide.
(This was just to save time cutting.)
Next, turn the sewn strip right side out and sew the ends.
After that, you will want to lay out your strips to determine how many you want on each panel and then straight pin them down for sewing. Keep in mind you will need to leave excess to make the ruffle.
This is definitely a time consuming project between cutting fabric, sewing the strips, reversing them, and then ruffling them through the machine. However, it ends up looking really great!