Pretty simple to use Brenno, simply tie it on and send it out making sure its not tangled. Try different anchor points on the boat to see what works best, i.e. to set up a good side on drift. I tie mine onto the anchor cleat and run it out through the bow rail and that sets up a nice drift angle, others find it better to tie off at the stern.
Also I think your main problem is that they are good for slowing your drift in the wind but not effective in current as the sea anchor is going to drift along at the same speed as the current/boat therefore creating very little if any drag. I find mine does little in strong current but works a treat in gentle to moderate breeze.
Cheers
C