Multi-tasking its the wrong way to think of it.
Each limb has to be independent of the other three.
Your right foot is the the down beat on counts 1 & 3
Your left hand is the "back-beat" in counts 2 & 4
Your right hand keeps the "time" with quarter or eight notes
You left foot adds accents to the high hats when ever you feel you want them. Usually most people keep the tempo with their left foot.
Start by SLOWLY playing quarter notes on your hi hats:
1,2,3,4 1,2,3,4 1,2,3,4 1,2,3,4
Then add your bass drum foot on 1 & 3
Once you have that down add your left hand playing the back-beat on 2 & 4
Then once you really have the feel for that you can open and close your hi-hats with your left foot.
Total limb independence is what you are going for which means all four limbs playing different parts of the rhythm you are playing.
Good luck and remember to ENJOY it!!