I changed the rear brake shoes in my 06 silverado 1500... now the brakes are spongy.. they have the self adjusting piece in the drums, how do i get them to tighten?

 

I have never had much luck with the self adjusting feature. When I first change the shoes, I adjust the brakes manually for the proper clearance. I have always had to periodically manually adjust the brakes afterwards. Maybe the newer models are better but this has been my experience before.
Spongy brakes sometimes mean they need bleeding. Might give that a try. Good luck.

 

Try the old back up fast in reverse and hit the brakes hard trick. If it works you hear a click or 2.