Adding a line between paragraphs

I'm creating my first page on my blog. I'm using the Visual vs Text method. I create a few sentences and then press enter 2 times so that I see a blank line before the next sentences I write. After I click Update, those extra lines disappear. I can go to the Text method and insert <br /><br /> at the appropriate place but I would have expected not to have to do this within the Visual mode.