How To Play Halo Reach Beta In ODST?

The Halo: Reach beta is now available through ODST. Bungie has just informed that the Halo Reach beta, which runs until May 19, is now live.
But how are you supposed to play Halo Reach Beta in ODST?

I can't play the beta for some reason.
Do all halo 3 ODST disks have the beta? Or do I need a special edition or something? Second, I know nobody will know for sure, but will the beta be linked with your gamertag?

The Halo Reach Beta is accessed through the main menu of the campaign disc. You do not need a code, you will play it from the main menu.

Just put in the campaign disc and it will appear in the extras section, if you try it now it should say 'preview the halo reach beta' which is just a video about it. The real thing should show up there when released.

And after you have played at least one match on Xbox Live, you will then be able to claim your “Halo Reach Beta Tester” Avatar Hoodie from the Halo Waypoint application.

In order to get started, start up ODST and click the “Play The Beta” option in the main menu. You’ll be prompted to download the beta client, which is about 1.15 GB. After you’ve finished the download, restart ODST and choose “Play The Beta” again from the menu.

There have been already some reviews and people are saying this game is a lot of fun.
The "Halo: Reach" beta highlights some of the dramatic changes that the developer, Bungie, has made to the franchise. Prime among these changes are load-outs and armor abilities. Depending on the game mode, players will be able to choose which weapon and ability they spawn with. This grants players the gift of flight with a jet pack or added stealth with invisibility. These types of powers used to be limited to in-game pick-ups, but now everyone has them right from the start of the game, and it really makes a big impact on how the match will play out.