Hands & Sticks,
Feet & Pedals

Hitting a drum with a stick or a pedal is the same as playing a note on an instrument.
(Drummers think about the length of notes but we can't really sustain a "whole" note on the drum as one note.  So we think about quarter notes, eighth notes and all that as the space between notes.)

Each surface (drumhead, cymbal, cowbell, etc.) is treated as a different note.

How we hit a surface modifies the the note.

We use "L" and "R" to indicate which hand is playing the note.

How you grip the sticks is really important ... but is best taught in a tutoring session.

Feet are used to play pedals.  

Usually "K" denotes the right (or dominant) foot, standing for "Kick" and indicating you hit the bass or kick drum pedal.  

"H" is used to denote the left (non-dominant) foot, standing for "Hi-Hat," but sometimes a second bass drum or bass drum pedal is played.

If we write "LRLL" that means we are hitting a surface with the Left hand then the Right hand then two Lefts in a row.

This doesn't determine the rhythm we are playing or which surface we are hitting.  

We can "LRLR" singles  because we use each hand a single time.  We call "LLRR" doubles for obvious reasons.   Most things drummers do with their hands is a combination of singles and doubles.

Drummers spend time practicing stickings without worrying about the rhythm or notes played.  The goal is to be able to play patterns automatically, then faster, then moving around the kit.