How To Change Blogger Code?

and why?
this blog has a certain role: to help beginners to understand how to change code, to make tests, to see what one can and cannot do with a blog @blogspot.com

i will do this only for seo purposes... because i have a blog about seo for beginners... and i need to interfere with blogspot code...

i'm not a web programmer, so if i can do something here... all of you will be able to do that...