You need Woogle (WoG editor) - download from this site. There are tutorials available too, also on this site.

Here

Needing a little help. I'm trying to create a new level and Editor only shows tool bar options in grey. I can't get anything to show up in any file to modify. What am I doing wrong. I'm sure it's some stupid little thing I'm over looking.

Have you Re-directed Woogle to WorldOfGoo.exe? Just direct it to your Custom World Of Goo, and select "WorldOfGoo.exe".* Then press the "Make new level" button to get started. There should be a tutorial around here somewhere to help you get the basics of things.

*If you have a mac, then I dunno, but if Custom World Of Goo is on your Desktop like I think it should be, then redirect it to the World Of Goo there. (World Of Goo.app, i believe)

I never tried the .exe file. I tried it while I was waiting for a reply and I'm good to go now. Thanks.

Please help! I can't put ocd in my level! I saw how to but I don't know what to put in the "value" box.

There are 4 types of values you can use: "" [This one is mine. -The Sign Painter], "balls,x" [collect X or more balls], "moves,x" [finish in X moves or less], or "time,x" [finish in X seconds or less].

Also, "moves,0" causes a glitch.