New blogger app!

I was so excited to see that there was a new blogger app.  I immediately came home and installed the app on both my iPhone and my iPad ... then I tried to use them ... It will only post to one of my blogs.  Maybe it's my fault for having more than one blog.  I have one for each of the classes I teach, and a personal blog - this one.  This is the one i want to be able to post to.  Any guesses how I can accomplish that?