If a User Interface is designed properly then a manual isn't required 
Seriously... I suppose you just have to do what I do - click on everything you see and watch what happens!
> clip off the first 2 minutes of a video clip
Click on the left side of the clip in the timeline and drag it to the right...
Or move the red/blue markers in the preview (left) window when a clip is being previewed, or play to the required point (or click on the time strip to move to that position) and press the red/blue marker buttons... that's 3 ways to achieve the same thing.
> remove a 3 minute section from the middle
move the timeline pointer to the start of the bit to cut out, and press the button to [split Clip] ... then do the same at the other end of the section to be removed. Your original clip is now three clips. Click on the duff middle bit and press the delete key.
If you watch the tutorial videos you should get a good idea of what's possible.