After extracting carrington-mobile in ur themes directory,just visit your site i.e slimkidhttp://ur-site-url/wp-admin
and login with the username and password u used wen u want to install wordpress earlier..After u hav login,just scrol down to where u see Twenty Eleven
and click on it,u will definately see carrington-mobile
logo like d one below,just click Activate, thats all..hope it helps? If yes drop comment and if u face any bug,count on me,just drop here.