New @me.com addresses can no longer be created. If you don't have an iCloud account you can use your Apple ID to create one (Lion 10.7.5 on a Mac, or iOS5/6 required) by signing in in System Preferences (or Settings)>iCloud with it and enabling Mail in the checklist. You will be asked to create an @icloud.com address.
If you already have an iCloud account you can add up to three 'email aliases' - these are additional addresses (not accounts) which deliver into the same inbox as the main account. (In fact it's a good idea to give out alias addresses, rather than the main address, because if they attract spam you can easily change them.) (Again, new aliases can only be @icloud.com ones.)
You should be aware before you start that once you've created an alias you cannot turn that address into a full iCloud account, move it to another account, or reactivate it if you delete it.
More information on aliases here: