I'd like to select an entire section of the map and copy everything in it. How do I sselect multiple items? I can't make it work.

you select multiple objects by holding down Ctrl and then clicking on the objects...

If you wan to select the WHOLE map, you go to Map > Map Properties
It will select everything in your map. Just close the window that comes up.

Also, in the 2D windows, if you have the selection tool active, then just use your left mouse button to drag and draw a rectangle over the items you want to select. Then press enter.

This will then 'select' all the items within the select rectangle.

Rob.