How do i Change launch folder within steam

[Arixl]

In short i've downloaded a script extender for my Fallout 3, i've got it all working but i have to enter the folder and launch it via actaully opening the folder. How do i change which folder my steam chooses to launch from as the default one steam has chosen dosn't run the script extender. I've tired having a look around google but could only find other info.

 

Fixed the problem, honestly i have no idea how, it just started working.