How do you loop a segment in After Effects ?

Hi Guys,

If I create a project and I create a small animation that is for instance 5 secs long, how can I repeat that little animation to go through my entire project without having to animate it every 5 seconds. In other words how do I loop something in A.E.

Here is 2 examples that I need help with:

1. I have a background that I fade in and out using the opacity tool. I fades in for 1 sec and then fades out for 4 secs. How do I repeat this FADE-IN/FADE-OUT cue for 20 secs, without animating it throughout the timeline ?

2. If I have a quicktime movie of a candle burning and it is like 7 secs long. How do I loop that burning candle for 20- secs ?

YOU GUYS ARE AWESOME WITH YOUR HELP!!! SUCH A GREAT FORUM !!
Cheers