If you've made the announcement that you're applying to business school only to have friends and family wince and ask if you "have to" take the GMAT test, it
How do I register for the GMAT?
Sign up for an account on mba.com and create your profile. This will get you into the system so that you have the ability to look at your choices for GMAT test centers and GMAT exam dates. It will also give you access to the free Official GMAT starter kit from the Graduate Management Admission Council (GMAC, the test maker) as well as two free practice exams.
You can go to GMAC’s “Create Your Account” page to get started. Once that’s done, you’ll have the ability to browse and pick your GMAT location and see your options for GMAT dates.