Try this tutorial if you have not been satisfied with other tutorials. There are many ways to explain abstracted subjects like programming language Scheme and the best way for a reader is strongly depend on his/her ability and background. (There is no absolute best way for everyone.) This is the reason that I have written another Scheme tutorial though there are many already.
The goal of this tutorial is to provide enough knowledge and ability on Scheme programming language to read SICP, which is one of the best text book on computer science. The book uses Scheme to explain subjects.