In the book "No More Dead Dogs," what does the main character, Wallace Wallace, learn about friendship?

At the beginning of the book, Wallace is the popular football star with a lot of friends. Throughout the book, the most important lessons he learns about friendship are what differentiates a real friend from the rest. 

One of the lessons Wallace learns about friendship is that real friends are there for you when you need them. This is demonstrated a few times throughout the book. After Wallace is unable to play football, most of his teammates don’t show up to help him with his yard work. He realizes that his teammates were only his friends because he was the star football player. "I'd always thought my teammates came to help because they were my friends. And they understood how important it was for me to pull my weight and help Mom. I never thought it had anything to do with football." This is a major turning point in how Wallace sees his friendship with his teammates. He realizes they weren't truly his friends. Later, when Wallace casually mentions raking his yard to the drama club, the whole group shows up to help him.

Of his football teammates, Rick and Feather are the only two who continue to support Wallace. Even though they have a falling out over Wallace quitting the team, Rick still shows up to tape the play for Wallace, since Wallace couldn’t be there. Rick tells Wallace, “I hate what you did, not you.” This shows that true friends will continue to support you, even if you don’t necessarily agree on everything.

Another lesson Wallace learns is that real friends are happy for you. When Wallace is released from his detention, he’s surprised because the drama kids are happy for him. "For some reason I couldn't stop laughing. Partly because it was funny that a detention had made me so loved. But mostly because their good wishes were 100 percent genuine." In comparison when Wallace returns to the football team during a rally, he observes that some of his teammates are sneering. Even though it doesn’t benefit the drama kids to have Wallace return to the football team, they’re still happy for him because as his friends they want him to be happy.