I have inherited my father's extensive Marklin train set. I played with it with him a lot as a kid and have a pretty good working knowledge of 90% of the old analogue system and wiring, but we never had a layout up long enough to install the signals and for me to understand the concept of how they work or run. Can somebody share their knowledge of their operation or recommend some reading or videos of how to properly install them? I know what their function is but I do not understand what signals go where, (what the colors mean) what track you need in conjunction with the signals, what the stopping lengths should be. How do you get them to stop and hold the loco and how does it know when to send the loco when the track is clear. I am assuming that requires specific types and pieces of track and I am wanting to learn. Any help would be very much appreciated.

Seconding Martti's suggestion.

As well, if they've been idle for a while they may be sticky (depending on how they were stored and what maintenance has been done before that).
Once you're comfortable with how to connect them to power and a control box, test them to see if they move semaphores and/or lights as expected.

PM me if you have some specific questions on them; I've been messing with mine for a while but am controlling them manually, not with control tracks.