How do I change the scene in the middle of an animation?
you could use the sequence editor- just add scenes and move them around at will.
How do I get to the sequence editor and then use it?
The sequence editor is built in to Blender, so there is no need for extra downloads. A tip about changing camera angles: Never devide different angles into scenes! A change made in one scene will not be copied on the other. Instead, render out lots of small movies(one for each camera angle), and stick it all together in the sequence editor.
PS
Acces the sequence editor by pressing ctrl-rightarrow a few times. Add clips/effects with shift-a in the sequence timeline.
Ok, now I’ve got Scene 1 and 2 set up in the sequence editor (set up while in Scene 1). Scene 1 goes from frame 1 to 390 and Scene 2 picks up at 391 till 550. I go to the Render Buttons in scene one, press “Do Sequence” and render. However, it just stops rendering at 390 and doesn’t do the second scene. What am I doing wrong?
Thx for the patience! 
just change the start and end frame in the display settings, so that it will render the correct amount of frame.
Martin
True, but in that case, it would be better to use a Set. Just have a Main scene, with all the objects except the cameras. Then, create a new empty scene, go to the display buttons and add the first scene as a set. Then, all changes done in the first scene will be transfered to that one.
Martin