If you ripped your fabric and then the edges were not perpendicular to the selvedge, you need to "pull" your fabric to make squared edges. Yank your fabric along the bias the length of the whole bias until your edges are perpendicular. I can not tell you how to figure out which bias to pull on, but, if you pull on one bias it will make your fabric more wonky and if you pull on the opposite bias it will straighten it. If you start on the wrong one and find it is getting worse, just pull on the other bias instead. It will eventually get the edged perpendicular. The fabric will work so much better if it is on the straight of grain, especially if you are using long strips!