I want to gain weight, but work out/get more toned?

Well I'm a girl and I'm pretty skinny and scrawny, like 5'3 96 pounds. I want to get up to 105 pounds, but I also want to work out (not serious work outs, just some cardio and crunches) so it's not all just fat building up. My concern is, do I have to eat a lot more calories so that when I work out I don't end up losing weight? Or is this all bs? I know that if I just work out now without changing my diet I'll still be scrawny, but I'll be skinny with muscle.... but I actually want to kind of bulk up (for lack of better terms haha).