1) Welcome to GT

2) You will find that this is a community with nothing but persons brimming to help you in all ways.

So here goes. Kudos for trying to learn rythms to songs that you like on your own and only after playing for 3 weeks. Commendable but not necessarily "rec-commendable"..... there may be some things you should focus on first that will help you better understand what you are trying to "learn".

The whole -- crawl before you walk-- philosophy. But if you are a typical "headstrong" guitarist (I am one also :) ). Then try these tips until you have a bit more experience under your belt.

Learn your power chords.

Follow the bass line. Typically most bass guitars will play the "root" note or the base note for the chords in songs. Learn the bass pattern add the powerchord version and you have the "easy" way to play a song.

When it comes to rythm patterns and such this can be very hard to explain in one post . Bottom line-- You need to practice basic rythms-- quarter notes, half notes, whole notes, eigth notes and sixteenth note patterns and learn your basic chords.

You will also find that down stroke upstroke combinations and palm/string mutings will benefit you in learning these rythms.

Confusing? You bet ya! I'd recomend tackling these basics -- you can find these on the web site, beginner booklet at a music store, or from an instructor to at least show you the "path" you must follow to acheive these goals.

****1 reason I am throwing alot of this at you is to give you the idea of some of the things that are "simple" still take weeks and months of practice to learn***

It is very common for most people who pick up the guitar to get discouraged due to the whole -- I want to pick up the thing place my fingers in certain areas and be the next Eddie Van Halen (or insert your fav here) but find out that some preparation needs to be done prior to "running".

Sorry if this doesn't help and I am not trying to "squash" your desire. I seriously recommend you at least spend more time playing (and picking the brains) of other guitar players you know-- don't ever be shy!!! all guitarists want to help fellow GTR players even if they are "better" than you-- or if you do not have any GTR'st to "learn" from spend a bit more time getting the basics underyour belt before going after the "white whale".

2 cents. Off my soap box