Computer nerd girl to the rescue!
When you are in the Edit Signature area, type your desired wording into the signature box in the place you would like it. Then highlight the wording you just typed and click on the icon that looks like a little blue globe with silver rings in front of it (5th from the right). A box will pop up to type your link into. Type (or paste) the link to your PTR here into the box and hit 'Okay'. It will then make your typed words the link!
I hope that helps.

If not, let me know and I will make a tutorial with screen shots for ya. (I do this sort of thing for my job, so it's no trouble, I love doing it!)
And THREE DAYS! WOW!!!!!!! I'm so excited to read your TR when you get back!!