'This page overrides a built in url' on tumblr?

[Chanté]

I've made a tumblr page with a custom theme, so that this page has a different theme to actual blog.
I want this page to be a tagged page, so anything I post with that tag goes on the page. I've created the page, done the custom theme, everything was set up perfectly. I tried to post the page, so it's mytumblr.com/tagged/am and it said that this page overrides a built in url?
What does this mean? Can I change it? I want to keep this theme, I like it a lot but I only want it on the tags pages. Is there anything I can do? I can't redirect, because then I can't have the theme I want, unless there's any way around this?

Please help!

[Sam]

One the left hand side of your dashboard, you’ll see your menu, click the last option which is "Customize"

That will take you to your blog, and you will see tabs on top of the page. Click "pages"

Click on that, then click on "add a page"

That will open a new window. For ‘Page Type’, click the drop down arrow, then click on "redirect"

For page url, add on to the link that will already be there, and write "self"
Next, type http://www.%28yoururl%29.tumblr.com/tagged/self or whatever you want to call the page.
(If it’s more than one word, put an underscore between the words)

There you go!

PS Make sure the pictures of yourself that you posted are actually tagged as "self" or whatever you want to call the page.