There are a million tutorials out there for an infinity scarf, so I'm not going to link to a specific one, and I'm also not going to turn this into another one. Find the one that best suits your fabric.
I found this sort of chiffon fabric (really not sure what it is) at Field's Fabrics for $3 a yard. I bought two yards, and then made two scarves, each one two yards in length, but half the width of the fabric.
I think they turned out very nicely, and they're a great length for doubling:
Love and Chandeliers,