When you have more than one tree in your account, when you login or go to the account screen both trees should be listed under "Families." You can click on the [Rename] button to give the new tree a "proper" name. Click on the [View] button or the Tree name to select the desired tree to view/edit it. Generally speaking work is saved automatically. If it isn't there will be a red caution reminder at the top of the screen reminding you to save.