Help

I'm a Boy and was at a normal weight with eating junk all the time. I decided I wanted a six pack, so I cut everything bad and only ate healthy and now im 6 foot 130 pounds. If I do ab excersises, and eat alot more will I just put on fat? I was planning on eating a crapload of peanut butter, and alot of eggs. Like half a jar a day of peanut butter. Is that ok for me to do? Is there a better way to put on lean mass?

Back up a little.....  Check your stats through this chart to find out a) what is a healthy (mid-range) weight for someone your age  and b) what your energy needs are.   http://www.bcm.edu/cnrc/bodycomp/bmiz2.html

To gain weight you need to plan on getting at least 500 cals more than your energy requirements... possibly even more than that.   ALL FOODS WILL HELP YOU GAIN MUSCLE IF YOU COMBINE THEM WITH SOME LIGHT STRENGTHENING EXERCISES.  There's no such things as 'unhealthy foods' or 'bad foods' just a 'poor diet'.  Cutting out junk was fine but, as you've found, you have to replace the lost calories with lots of other foods or what you end up with is an unhealthy diet.  

Take your calorie target and split it into three main meals and three or four good-sized snacks.  Yes you need peanut butter & eggs..... AND..... bread, pasta, meat, fish, vegetables, fruit, chocolate, potatoes, nuts, cakes, rice, dairy products (full fat preferably), beans, cereal bars, fruit juices, oils .... as many different kinds of foods as possible.  I've put chocolate and cakes in there deliberately.  Obviously you wouldn't want to live on those 100% but, in reasonable amounts, they are good things to include in a healthy diet.

If you're particularly young and live with your parents then talk to them about what you want to do.  Ask for their help in creating suitable menus to help you gain back the weight you need.  And if you struggle with your diet either physically or mentally then consider seeing your doctor