Visit the Wizard 101 test realm website, and download the test realm to gain access. As of 2015, you must have an active membership or have made a purchase of $6 or more in the last 30 days as a crowns player to access the test realm. Free-to-play players do not have access to the test realm in the game.
Use the same password and login name that you use for the regular game to log in to the Wizard 101 test realm. Test realm items such as crowns do not carry over into the regular Wizard 101 realm. However, you cannot lose items in the test realm that you have in your live realm account. Leveling your characters through the test realm also does not affect your characters in the live realm, and game administrators have the right to change your levels in the test realm at their discretion. Accept these terms by checking the box on the Wizard 101 website to gain access to the test realm download.
The Wizard 101 website also has a page detailing the new features in the current test realms. Wizard 101 test realms often feature new pets, crafting and other activity features, menu features and various other updates.