Hey, iv been following the lessons on this website for about 3 days now, and i must say that i love it! I'm truly thankful for finding this place

Now iv followed all the lessons fine with minimal errors up to lesson 12. After that and into 'Perceptron Training' though, I got lost. It mentioned something about viewing a different lesson called neural network before going into it, and so is there a link to it?
P.S:
After about a day of being here, i convinced three other of my friends to join along with me and learn C++ (were all pretty interested) and live really close by each other. Were all 16-17 years old and really want this little group of ours to be a success, but are the chances low? Is there a good chance we will lose motivation and eventually just stop (if the lessons get too hard) or could 4 16 year olds make it to a pretty high feat in C++ :s? So far we met up and watched the lessons together for about 3 days and feel pretty good, but i sense things will get really complicated soon...