Welcome to Halo Answers. What would you like to know?

If you mean the beta, then you need Halo 3: ODST and a Xbox LIVE gold subscription to download the beta off the Xbox marketplace. After you've finished downloading it, you can then play it from the main menu in Halo 3: ODST.

Ad blocker interference detected!

Wikia is a free-to-use site that makes money from advertising. We have a modified experience for viewers using ad blockers

Wikia is not accessible if you’ve made further modifications. Remove the custom ad blocker rule(s) and the page will load as expected.