How do I add a link to my tumblr?

I’m wanting to put a url to an regarding me inside my data (with this theme the idea won’t manifest with if i just add a page) and also i keeps likely to my url/my url/about, when all i want is the url/about.
Does anyone know very well what to do

<a href="LINK HERE
In the event you put that in your customize, it would be good.

There are a few nice fall down choices too.****

The link to create a sliding off the road out move down:

http://freetexthost.com/10qpe2wlmw

The link that could take to a typical customizable decline down:

http://www.myspacegens.com/handler.phpgen=redirect.