I always enjoy Dave’s humorously accurate answers, but it might help to clarify what he was getting at … using AE for cuts editing is like using a sledge hammer to drive nails so you might consider using video editing software, which AE is not, although it naturally shares some capabilities with video editing software.
Try splitting the layer (including its audio), then delete the portions you don’t need. You can find “split layer” in one of the menus and I think the short keys are CTL+ALT+D or Option+Apple+D.
It might also benefit you to know that AE is not the type of software one learns through intuition alone … you will have to use the manual, help files and endless other resources available for AE at some point(s) so it’ll save lots of time to do so from the beginning.