Any tips on training a puppy?

I took in a 8 week old Boxer puppy 1 week ago for a friend, I have never owned a dog before so I am still new to everything. I am currently trying my best to find good, reputable trainer for him and enter him into puppy kindergarten/training classes but I am having a hard time doing so, I thought that until I could find one I could go ahead and start with some of the basics... except I don't know where to begin.

So far he is doing wonderful with potty training, he hasn't had an accident for 5 days and he hasn't attempted to chew on any furniture for almost the same amount of time. I use positive reinforcement only, he has very weak nerves and cannot handle being yelled at.

I can get him to Sit for me if I hold a treat over his head and move it back, so now whenever I hold up a treat I will say "Sit" and he sits. He is very smart and very willing to please.

I don't really care if he knows tricks, I want him to know the basic commands such as Sit, Stay, Down, Off, On, Quiet, Come, etc.

I work with him on training for a few minutes several times a day, I end it when he acts like he is getting bored or tired, I want him to find training and obeying a fun, good thing.

So can anybody direct me to a website or give me any information on how to teach him the things listed above and any tips?

Thanks.