You can use this tutorial for the first step if you want to do it: Write Yourself a Scheme in 48 Hours by Jonathan Tang. http://jonathan.tang.name/files/scheme_in_48/tutorial/overvi...
A compiler, if asked to "execute" itself a million times will generate code that is still reasonably fast.
An interpreter, if asked to "execute" itself a million times, will generate code that is a million times slower.