I think the subject is enough of a question.
Presuming you're a cadet, this is information you should be asking your squadron.
Log on to eservices, select: "Cadet Programs" (from the left-side menu) then click on: "Cadet Online Testing"
If you are referring to the Spaatz exam, it can only be accessed by a proctor appointed by your wing\cc. When you're ready, your squadron commander must notify the wing commander to set things up. After that's completed, you will be given information to schedule the exam with your proctor.