Firstly Assalamu alikum ,
Its really difficult to learn any language alone and was consume much time , than going to classes and practising it with friends and show how is the perfect way to pronounce and talk in it, but you can learn it alone using Books , sites,.. there are many great Arabic Sites will help u insha Allah at ur start e.g.
-http://languageguide.org/arabic/
-http://arabic.speak7.com/
-http://www.learn-arabic-language-software.com/
Hope that help u insha Allah , All the Success for u ^_^