FreeGameDev

Where can i get the supertux level editor for 0.3.1 - 0.3.4 please?
And i got windows 7 home premium

It depends on what operating system you have. What is it?
you can check these links though:
viewtopic.php?f=67&t=2777
http://supertux.lethargik.org/wiki/Download/Unstable
and the code if you want to compile: http://code.google.com/p/supertux/sourc ... epo=editor

I installed supertux.editor-0.3.4+GIT_20130831thou the link you gave me. but when i click to run it does nothing.

Sorry I can't help much here. The editor is not my area. I'd suggest going on our irc channel and asking for help there. You might have to be patient because there aren't always people active on there.
#supertux on freenode
or http://webchat.freenode.net/?channels=supertux for the online version