I've noticed that some people find it a bit tricky to join the guild here at ggFTW. I've decided to help a bit. (All images will be under spoiler tags because they're kinda big.)
First of all, make sure you're logged in.
This is very important, despite what the screenshots say.
Second, go to the "Guilds" section (circled in red) and click on it.
Third, find "Ecks.T.C" within the guilds (circled in red) and click on it.
And finally, under "This Guild" (on the left side of the page), click on "Join Ecks-T-C" (circled in red).
Voilą! Once approved by a mod, you've just joined the Ecks.T.C. guild! Congratulations!
I hope this helps. :)