They're going to give you an as of yet undetermined number of questions, which will likely be based on the EMT curriculum. Once they give you the questions, you'll want to answer them correctly. The computer will then determine if you meet minimum standards or if you suck. It will tell you it's decision some time either later that day or the following business day. Hope you fall in the former category.
Test on August 9th. Or as soon as you can schedule a date. Don't put off to study. My anecdotal experience as an instructor: students who put off the test tend to do worse.