I didn't make it.

Ok then.
Step 1: Open paint (Photoshop is #Mainstream)
Step 2: Click the paintbrush
Step 3: Get creative and make some clothes
And voila your avatar has some clothes and can be seen in public without being arrested and fined.

Let's just imagine she's wearing a strapless dress

I'll try, this is as hard as the Google+ situation though..

Ms Paint lessons available in this video: http://www.youtube.com/watch?v=gmEXtOC14tQ

I'm not prepared to touch any drawing programs until I have my graphics tablet set up

What graphics tablet do you have?

^

Wacom Intuos medium

The pen and touch one