URL:Uniform Resource Locator, an HTTP address used by the World Wide Web to specify a certain site. This is the unique identifier, or address, of a web page on the internet. URL can be pronounced "you-are-ell" or "earl." It is how web pages, ftp's, gophers, newsgroups and even some email boxes are located.
url example :
http://www.insidetheweb.net
http://www.msn.com
http://insidetheweb.net/myblog

To locate your blog url , sign in to your account and select the specific blog that you want to know its url (from blogs mamnger) and go to settings >> blog address :

 

from the picture i know that's my blog address is : http://www.insidetheweb.net/myblog