How much should I eat if I want to gain more muscle m?

So...my arms seem like they're getting more tone, but not really that much bigger. I've read that I'm not eating enough. But the thing is I don't know how much I should be eating. I understand that I should eat a lot, but how much exactly? Because I don't want to over-eat and get fat. I'm 6ft and 177 pounds. I try to run about 4 miles everyday. Im kind of really sub-conscious about my weight bc I used to be pretty fat :P. *If it matters my workout schedule is like- MON-Triceps and chest TUE- biceps and back WED-off THURS-shoulders FRI-legs SAT/SUN-rest. Thanks