Good morning Mike.
Click on the "User CP" link right above your username on the left side of the page. Look down the left side of the page and you'll see a heading that says "Settings and Options". Under that click the option that's labeled "Edit Signature" and you'll be able to create a signature.
With that said, normally you're required to be a member for at least ten days and have at least five posts before that option is enabled. I checked your profile and it shows that you're able to create a signature. If you're still not able to create one following my instructions above, make a couple more posts to get to 5 total and then log off and back on. This should get you set up.
Let me know if you have any more problems.