if you want to learn how to program in C, then I suggest that you jump straight in.
there isn't much that you can't ask for help with fi you get stuck, and it really isn't that hard once you've gotten your head around the basic concepts.
If you want to start with a different language first, then move onto C, i would suggest PHP, since you can write terminal line program, the syntax is almost the same (though dramatically simplified),
a good place to start is on howthingswork.com they have some good beginner C tutorials.