There are a couple of ways of finding out what your blog address is.
The easiest way is to click on the header at the top of your blog and then look in the address box at the top of the page.
Your blog address always ends .com
If there are other words and numbers after the .com part, then you are on a specific page of your blog, whether that is a post or a search results page.
There is another way to find out what your blog address is though.
If you click on Design and then Settings, your blog address will be shown at the top of the page where it says Blog*Spot Address.