If you need to gain weight, you should do it in a healthy way.Don't just eat a ton of junk food like pizza, and gulp down sodas.
You need good sources of protein;
Yogurt(particularly Greek yogurt)
these are also good sources for healthy fats
You are getting carbohydrates from the oatmeal, and beans too of course.
Nuts, and Nut Butters
You have to eat vegetables, and fruit as well.
You can also make protein shakes.
It's often made from whey.But you can get many kinds of protein powder, and weight gainer powder.Can you have dairy products?
You can put a few scoops of protein powder in a blender with milk, and a banana, or strawberries.
Eat eggs, and oatmeal for breakfast.
Make peanut butter, and banana sandwiches.
Have chicken,rice,and veg for dinner.
Cottage cheese at night.
Just a few ideas.
If would help if you would tell us your age,gender,height,and weight.
And also if you have any food restrictions.
If you're tired of starting over,stop quitting.