how do i make an avatar?

If you're asking how to literally make one, then your best bet is Photoshop.

If you're asking how to upload one to H.com, then um, that's a little more complicated. You have to host it somewhere (tinypic.com is a good place) then paste the URL somewhere into your personal profile. I don't remember where.

There are different ways of doing it. Here is a convoluted way, but it works:

Let's assume you have a picture on your computer, let's say a .jpg on your desktop.
Upload the image to a site such as http://photobucket.com/
Once the picture is uploaded to something like photobucket.com, go to My Controls on the top right of this page, select Edit Avatar Settings on the left, and then where it says,
Enter a URL to an online avatar image, paste the link to the image on photobucket, then click Update Avatar.

Avatar Settings