If your talking about how to create a new blog on your account go My blogs on the left of messages which is on the top of the page that looks like a letter, sensa69 it will drop down some blogs and an option which is last called Create a new blog click that to create a new blog.
How do you add a another member to a tumblr blog?
This will not work on your main blog “the first one you created” it will only work for your other blogs, on your dashboard click your blogs name on the top where your other blogs are, on the right under posts click members. It will come up with a search bar, type in an email that you would like to be a member of your blog, it will only work for people who used their email for tumblr.