Carol,
I use a address label to center my designs. I make a cross mark on it and then I put it on a t-shirt lets say. I then hang the shirt to see if it looks crooked. And then when I think it looks good, I take it to the emb. machine and stitch it out making sure the cross mark is in the center of the design. A cross mark is drawing a line down the middle and then down the center. I hope I've helped. Connie