The same as any other plant - you cross two different species, a species and a hybrid, or two different hybrids!
Do you mean to say "How do I pollinate Cymbidiums"? That's a matter of removing the anther cap and collecting a pollinium from one flower, then transferring it to the stigmatic surface of another flower (which is underneath the column). You can use a toothpick for this. Then you wait for the pod to ripen, and either sow the seeds yourself or send them in to a flasking lab.