All you need:
6 yards of fabric minus 10ish inches (if you want floor to ceiling curtains)
You can always do them shorter...just guesstimate by holding the fabric you have up to your windows.
I got this fabric from Whole Port.
Start by laying the fabric out on the floor (leave it folded lengthwise for convenience) and if you have 6 yards cut off about 10 inches. Then cut the rest in half.
Now you have 2 panels, one for each side of your window.
Sew the edges of each panel (length of the curtain) just to finish the sides. You can tuck it under twice if you prefer, but then you will have to pin it and it will take you a lot longer.
Next you can either sew the top or the bottom of the curtain, doesn't matter. I did the top so in the end I could make sure the bottoms were the same length.
You will want to fold it over about 2 inches (give or take depending on the size of rod you will be using)
Then the edges will need to be folded under to finish it off. Pin both folds together- this saves you a step of sewing and pinning one fold at a time!
I fold and pin both ends of the curtain first to make sure they are equal, or you can use a ruler if you are more of a perfectionist than me :)
To finish the curtain, sew the bottoms, but make sure they are the same length- you can lay them out on the floor and check.
Then fold the bottoms over twice to prevent fraying and pin
Sew and hang!