Paint it on the inside (the side that you put the ink and squeegee from). The filler should be such a thin layer that it does not really matter – you want as smooth as possible.
Well, do it yourself kits are reliable, but you don't necessarily need everything in the kit. And they cost about 140$+ :x
If you're interested in this as a hobby, or you're wanting to test the waters, here's a simple tutorial for making one color print shirts -----> http://www.instructables.com/id/Screen-Printing%3a-Cheap%2c-Dirty%2c-and-At-Home/step4/Burn-Your-Image/ You'll need the following to follow it;
a screen (22$)
total= 70$ max.
The ink and emulsion can last you a while, and you can reuse the frame so long as you have the chemicals for washing the emulsion off.
As for the materials to follow the tutorial, you can order them here -----> http://www.silkscreeningsupplies.com/site/799934/product/W2024156