Hello strongoak52, and welcome to the forums.
Acording to Bill (ihc6480) you throw them in your wife's flower bed and wait a year or so, then wait for the screaming.
I have not tried opuntias from seed yet, mostly because they are so easy to start from cuttings, but they certinly can be grown from seed. I've been told to Try soaking, soaking then drying, scarifying, stratifying, and to Just keep trying.
Someone will be by eventualy that can actually help.