Moving the selected clips around on the timeline is as simple as clicking on them with the left mouse bouton and dragging them around. You can resize clips directly from the timeline. Simply move the mouse cursor to the the beginning or end of the clip you want to resize. Now, click and drag with the left mouse bouton to resize the clip.
Resizing a clip changes it's in and outpoints. If you reselect the clip and look in the clip monitor, you will see that the in and out points on the monitor show the new positions.
It is not possible to resize a clip past it's length - if a clip is 30 seconds in length, then you will not be able to resize the clip so that it finishes playing 35 seconds into the clip!
When you are resizing and moving clips, there is a handy "snap to" feature, which will snap the edges of clips to other clips and the current seek position. This is useful for quickly lining clips up with each other, but in some cases may not be what you want. You can turn this behaviour on and off using the Timeline->Snap To Border menu item.