it will take a while to understand the add ons and so forth. Its kinda like building an OS from scratch.
My advice is to go to cydia, click on the make my life easy banner. just do that for now, much later topic.
then go to search and look for the app (rockapp).
register and so forth.
when you have an account established look through cydia and rock for certain apps, themes, ring tones and mods. Rock seems to have better review on the apps and such than cydia. look over the review and theywill tell you if its compatible with ios4 or not.
plan on crashing a few times.
its a learning experience and does take time.
but to answer your question it is you. but we were all at the same place as you are not to long ago.
your best best is to visit this site in the iphone hacks section and modmyi.com as well as thebigboss.org, oh yeah iclarified.com has some good tutorials.