Getting lower in level editor[solved]

[clock123]

When I'm creating a map in level editor, I start by creating in the center things, and when I want to get lower, I mean by doing first flower or outside area on the ground, I can't see everything infront of me, I want to know how can I make that place the center or at least go down with seeing everything and without having to stretch your eyes down because you can barely see. here's an example pics.
http://imageshack.us/g/11/asdasdassdas.png/
the first two are the one's that I want to change so I can see like this :
http://imageshack.us/photo/my-images/708/30445765.png/

I want to see the same as the last picture at lower levels in the editor, how do I do that? , thank for helpers