draw your shapes on the paper side of your wonder under (and your fusable choice is fine, it washes up nicely and is one of the older - been around for many years fusables) then rough cut the shapes out.(i leave 1/4"-1/2" around my shapes) and press to the back of your fabric choices then cut out carefully on the lines. peel the paper, place on your background and press in place then stitch around the edges using your choice of stitch, zig-zag; blanket stitch; straight stitch are all frequently used to stitch your appliques down.
fusable choices are as personal as every other aspect of quilting. for me i do not like steam a seam, but have been using wonder under for many years, and sometimes i pick up heat n bond lite. regular heat n bond tends to get very stiff, and stay that way. most of the fusables do soften up when your completed project is washed.
good luck and have fun with it!