To tell if you logged in as "user" (non-privileged account) or "root" (super user, the most privileged account possible) type the command "whoami" in xterm, the response will be either "user" or "root". When you first open xterm you will be logged in as "user", and you have to execute the command "sudo gainroot" to become "root" (the command prompt will also have a # appended to differentiate "root" from "user").

While logged in as "root" you can return to the "user" account by typing the command "exit" which logs you out of the "root" account - if you type "exit" when logged in as "user", xterm will close as you have now logged out of your session!

I'm not sure why directory creation (mkdir ~/a2dp) is failing, make sure you execute this command when logged in as "user".