One large egg has about 70 calories, that’s not too bad for putting on weight. Each one also has 6 grams of protein; this is also quite good for putting on weight, if you work out that is. If you want to gain muscle mass then protein is what you want, if you’re simply looking to bulk up your stomach for some reason (and you never know with this site) then you may want to stick to fried foods.
The problem with eggs is the cholesterol, about 190 mg in one egg, which isn’t really a problem unless you eat a lot of eggs. Doctors will tell you to eat about 300 mg of cholesterol a day, that’s less than two eggs. Since two eggs is only 140 calories you would need to eat a lot more than two eggs a day and that would be bad eventually. I’m not going to say you should not eat more than two eggs a day, just don’t make a habit of it.
If you want to gain weight then try different proteins, chicken, and fish, especially tuna, are great sources of protein. Before a work out make sure you get some carbohydrates in you to use for the energy required to get a good workout in. If you’re lifting weights you need fewer carbohydrates than if you were going for a run or something similar.
Hope that gets you started, here are a couple other answers you may be interested in.
Weight Gain
Six Pack
