Modified tutorial from about.comSupplies
Muslin (for lining)
4" Drapery header tape
Blind hem foot (optional)
Thread that closely matches your fabric
Install your curtain rod. Install the brackets so that the rod will sit 4" above the window frame, and extend 4" beyond the edge of each side of the window.
Measure from the rod to where the you would like the bottom of your curtains to end. Typical lengths are 63", 84" and 95". Whatever you determine will be your finished length.
Measure the length of your curtain rod. For grommet curtains you want panels that are at least double the length of your rod. Most likely you will be using the full width of your fabric, which is typically 44-45". From there you need to determine how many panels are needed for one window.
Cut your fabric and lining. (Make sure to wash, dry and trim selvages before cutting).
All measurements include a .5" seam.
Fabric width: Full width of fabric [If curtains are smaller than the full width, the calculation is finished width + 4"]
Fabric length: Finished length + 8" (hem) + .5" (top hem)
Lining width: Fabric width - 3"
Lining length: Finished length - 3"
Using a zig zag stich finish off the top and bottom of fabric.
Sew in the bottom hems.
With your fabric laying right side down, fold up the bottom 4" and press. Then fold up another 4" and press. Pin your hem. Sew with a blind hem stitch. A straight stitch can also be used but a blind hem looks more professional.
With your lining laying right side down, fold up 1" and press. Then fold up another 1" and press. Pin again and sew in place with a blind hem or straight stitch.
Press in your top hem.
With your fabric laying right side down, fold the top over a half inch and press.Step 8:
Sew your lining and fabric together.
Put your fabric and lining right sides together. The lining should be 3.5" from the top and about 1.5" from the bottom. (We don't want the lining running all the way to the top because we need to minimize bulk for the grommets.) Align on one side, pin and sew together with a .5" seam. Pull lining over to the other side of the fabric and repeat.
Turn curtain right side out. Your fabric will automatically turn over to the lining side about 1.5". Iron the curtain so that the fabric is even on both sides of the lining and pin to prevent slipping.
Fold in the raw edges on bottom, press and pin.
Cut a piece of drapery header a little smaller than the width of your finished curtain. Smooth out the lining fabric and pin the header onto the top of the fabric and lining.
Sew the header down with two rows of horizontal stitching.
Sew down each side of the curtain with a straight stitch making sure to catch the lining.
You must use an even number of grommets or else you won't be able to hang your curtains properly. The typical spacing between grommets is 4.5", but that isn't a hard and fast rule.
You will receive a template with each package of grommets. Place the template inside of your stitching and about 1" from the top of your panel. This is where you should mark for your first grommet.
Make sure the spacing between each of your grommets is even. Determine the appropriate spacing and mark where you will place the grommets.. As you see in the picture my spacing was 5". So I marked a hole every 5".
Cut an X inside of each hole with your rotary cutter and then cut out the circle completely with scissors.
Insert your grommets.