Mama is 100% correct. Id jsut liek to add that you may or may not need to climb those mountains. typically the tasks of developing graphics, slicing and coding the layout, and developing the backend (php and mysql or whatever the case) are split between multiple people or multiple teams of people. Few and far between are those that do all of those jobs well. Not so say that those that doo all those things well arent in demand but they are hard to come by and by o means shoudl you feel forced to be one of those. However, if you goal is to work freelance, the larger your skill set the larger your pool of potential projects. Of course you can always find people to contract for the stuff you dont know as well.