Problem with permissions in setting up template routes

Relative newbie to EE here. I’m trying to set up URLs on my site such that instead of this:

http://mysite.com/blog/entry/title-of-blog-post

I want it to look like this:

http://mysite.com/blog/title-of-blog-post

I understand Template Routes are likely the way to do this; however, for some reason I can’t access Template Routes.

EE documentation says to go to Developer ‣ Templates ‣ Template Routes, but I don’t see any option for Template Routes when I try to go to that page.

I think it might be a permissions issue because when I try to go directly to /cp/design/routes, I get a “You are not authorized to access this page” error, but I’m not sure how to resolve it.

What am I missing here? Any advice is much appreciated.