The best and easiest way I've been able to do it is to get oatmeal (quaker is the type I use) and bakers yeast.
I put some dry oatmeal in whatever I'm making the culture in and then sprinkle water on top. You want the oatmeal to be soggy, but not so much that theres extra water in the cup *if you have extra water either drain it or add a little more oats)
then put a spoonful of old culture into it and mix, then sprinkle bakers yeast on top.
I dont cook mine at all -- this makes it last longer, but still is just as effective as using cooked
You should start seeing new worms in 2-3 days. Reculture in 2-3 weeks.