Here are some answers to your map making question, and some really good map making tips. If you have a question not listed here, please post it in the forum so we can address it and possibly add it to the page.
If the question does not have an answer or a link, I don't have the page for it yet. But it will be up in a couple of days.
If your are brand new to Map Making then you might want to check out this Basic information sheet by Slaughter*AUS*
Set the player start markers to a height of Z 100/000 or higher. Be careful though, setting it to high, with some weather settings, will get some very bad graphics during the intial part of the chute in.
How do I zoom in the map editor screen?
Use the "page up" and "page down" keys.
Hold the Shift key down while holding down the "right mouse" button and move the mouse left or right.
Why do I/flags pop to the surface when I/they spawn underground?