Step 4: Eat Good Stuff
Ever seen someone spend $1000 on exercise equipment, use it for two weeks, and then let it collect dust in a corner? Yeah, me too. Don't be that person. Just buy a little at a time and as you change your lifestyle to a new weight-gaining one, you'll end up buying more as you need it.
One small bottle of powdered whey protein (Sam's Club has the best deals, then Wal-Mart) is a good start. Small bottle. Also, eat more green and colored vegetables. Broccoli is a really good one.
You can eat a lot of rice (brown is better), whole grains (like cracked wheat), and eggs. Eat at least 6 eggs at a time. Tofu is an okay vegetarian substitute for protein but it costs quite a bit more.
In your weight gainer powder, you want quality protein. There are some "weight gainers" that are mostly sugar. I accidentally bought one. Lots and lots of calories, but they were empty calories. Sugar is fine, but you need more protein than anything else.
By the way, you will probably see some bowel changes with diet changes. I suddenly had regular bowel movements at 10AM every day.
Here are some good 1000 calorie shake recipes. To help you get started.