I don't have one handy ATM, but if it helps, I think of the process sort of like folding paper to make snowflakes, only instead of cutting out bits of paper, we're marking off and dyeing bits of the fabric.
To only fold the front of the shirt, fold it in half with the side seams together, so the front of the shirt is on one half and the back is on the other half. Then you can mandala one side of the shirt (or one side one way and the other side another way!).
I use my husband's old undershirts to practice on - lots of fabric, and usually a nice light weight (and broken in too!

) so easier to fold.