These rockets use commercial Estes engines, I will hopefully make my own engines pretty soon and get a page on that done also. This page shows pretty much the same thing.
Estes rocket engine (C or D size)
Fused salute/other payload
Scrape out the clay from the top of the engine. I have used D's with Class C shells and C's with cobs so far. Be sure you check the delay on the engine. A C6-7 for example has a 7-sec delay, meaning the rocket will probably be on its way back to the ground when it goes off. You DO NOT want this to happen! Use C6-3's if possible, if you only have 7's you must scrape out some of the delay mixture (gray/silver powder between main propellant and ejection charge) so it will go sooner. Now put the salute so the fuse touches the ejection charge. If using a cob in a C, it fits almost perfectly. Glue the payload to the engine and let it dry. Make sure it's on straight or your rocket will not fly properly (which could be very dangerous!). Once that is dry, tape the whole thing to your guidance stick (I used skinny dowels). You can glue the engine to the stick to be extra sure it will hold. Tape seems to work fine for C's, but for D size I'd definitely glue it along with taping.
Read this page for info on performance and payloads.
C6-3 with cob, not yet wrapped in tape: