I'm going to assume this floor has already been "finished", if not then disregard "scuffing"!

Depending upon what shape you want, you can use blue 14 day painters tape to outline the shapes you want, then lightly scuff the surface of the floor in the area to be painted with sandpaper before you apply your paint. You can use a brush to apply the paint, or a sponge for an "old" look, or a sponge brush...

If you want to do a circular pattern, try cutting a stencil from mylar, or even use butchers papers to make your pattern. If your heart isn't set on paint, you can mix artists oils into poly and use that to create your design. Be sure to mix your oils into about a quarter cup of poly first until completely dissolved, then add more poly until you get the amount you will need to complete your project. Whatever your choice, paint or poly, be sure to put at least 2 coats of poly over your design when finished.