i took an schwinn speedster, not sure what year but a good guess its a '76, took most of it apart to clean it all up and replace old nuts and bolts. i took off the chain to let it soak in vinegar and now i have no idea how to put it back on. im sure its a simple problem, but ive never done something like that, at least not since i was a young kid i would imagine. can anyone help me, some helpful tips. basically, how do i put a chain on a 3 speed schwinn speedster from the mid '70's?

Are you asking about how to put the master link together ? if so put the chain around the chainring (the front gear ) and around the rear gear (on the wheel ) , take the master link with the pins thou the backside of the two open link of chain ,put on the cover link (the one with two holes in it ) on it and press on the chip and you good to go.

That's if the master link is the clip-style. Most of the Schwinn 1/8" wide chains (generic for 1-speeds and 3-speeds) used a master link that needs to be sprung sideways to install the plate.

Of course, the first question should be: how did you get the chain off in the first place?