I think seahorse.org has a lot of info. I think most people set up a "lagoon" type tank with macroalgaes and maybe a goby. LR is in the sump. Flow is gentle. You could also try the seahorse forum on Reef Central.
I did buy the book
Dwarf Seahorses a while back, because I eventually want seahorses. It's not a bad book, but to stock a tank would have been somewhere around $500, and at that point I had no SW experience. Now that I do have experience, I have no time to care for them
I definitely do want a lagoon tank with seahorses some day. I would recommend the book, although it really only talks about dwarf seahorses. They're apparently some of the easiest to breed.