The m7b5 chord is also called the half-diminished chord and is often written with the symbol Ø, thus Cm7b5 can be written CØ. It's also written Cm7-5.
We'll leave out why it's called a half-diminished because it's too complicated and doesn't affect its usage.
The main two ways of playing it as a rhythm chord are:
The root C of the first chord is on the 5th string and of the second on the 6th string.