I have an adjustment layer with a blur on it but i only want the blur to show up on the certain parts of the footage. Is there a way to start and stop the blur one the adjustment layer over the course of the footage?
You can keyframe the blur amount, trim the layer's in and out points, keyframe the opacity of the layer, or put a mask on the layer and keyframe its path.
Really, it all depends on exactly what you're trying to do.
This is very basic stuff though. If you're having trouble with something like this, you are probably going to run into a lot of other problems too! I'd highly recommend going through some of the resources here: Getting started with After Effects
Got it thanks!