Welcome to the furom [your name]* !
This topic maybe help you :
http://goofans.com/forum/world-of-goo/mods-and-hacks/3001

* (Sorry, but saying his name just doesn't sound right. We can't change his name, but we can try to minimize its use. -puggsoy)

I love your username, it just made me laugh, and it made puggsoy uncomfortable so that made me laugh even more! Anywho:
Click the "World of Goo Addins" at the top of the page, in the dropdown, choose "Upload an Addin". Once you created the page, in the "Downloads" tab, there's a link that says "Upload a new file".
Hope that helped, Du- I mean, my good sir

That's what I wanted to write - if you still struggling - If you do what momo said and you dunno how to input your goomod file for installing on your page then:

Go to Downloads, click Upload file and open your goomod. It should work... Now if you want it to be public just on the top your page there is written Request this addin to be published so click on it and wait till moderators publish it. If there are some problems and that moderators dislike about your addin they will tell you in the addin page - to get there go on your account and find your Unpublished addin. Hope you understood, than you.

Not only did it make me uncomfortable, but MOM4Evr previously asked him to make a new account with a G-rated username.

Something like MentallyChallengedPosterior maybe? Trolololololo

More like "DumbCucumber". Puggsoysoysoy