Let's look at some basic co-ordination patterns that you can also use as warmup exercises.

EXERCISE 1.

The first exercise just gets your hands and feet used to playing between each with 1 stroke each. So just play

EXERCISE 2.

The second exercise is the same as the first except you play 2 strokes alternating instead of 1.

EXERCISE 3.

Exercise 3 uses 3 strokes alternating between bass drum and snare drum, think of it as triplets.