Instructions
Turn on your Xbox console. If you are logged in under a previously created Gamertag, log out.
Go to the Marketplace and select ̶0;Join Xbox LIVE.̶1;
Fill out your information, such as address and birthday. You will also need a Windows Live ID and, if you have a previously created Gamertag, a new email address.
Select the Silver Xbox LIVE account, which is a free Xbox LIVE account but does not have all of the features of the Gold subscription. You will be asked if you are sure you want a Silver account. Select ̶0;Yes.̶1; You will then be offered a free one-month Gold trial.
Accept the one-month Gold trial. You can now use all of the Gold features for free for a period of one month.