Hi there. You might find the video tutorials
helpful for getting a hang of the basics of the program.
To edit the end of your clip, there are several ways you can proceed. the first is to set the in point where you want it in the media browser. After you have imported the clip, click its thumbnail to select it in the media browser, and it will appear in the preview player at the top of the Toolbox. There you can scrub or play to find the in point you want to use, and use the In Point button (looks like a left bracket) to set the in point. Use the Out Point button to set the out point, then add the clip to the timeline.
The second, is to use the Knife tool (on the top left of the timeline; it looks like a knife) to cut the clip where you want, then delete the part you don't want from the timeline.
The third is to use the crop tool (top left of the timeline, looks like two arrows pointing away from each other) to drag the front end of your clip to the right, to remove the portion you don't want to include.
You can't zoom in on the timeline, though there is a scroll bar at the very top of the timeline that can be used for moving over large areas more quickly. As far as seeing more of the timeline vertically, there is a handle at center between the timeline and canvas that can be used to drag the timeline taller or shorter, and each layer has collapse arrows that can be used to reduce the amount of screen it takes up when you aren't using its controls.