Officially they're only legal if they contain a very minimal amount of THC, 0.2%. But of course that is useless.
They're sold in many shops as well as online. Very important is the dosage though, because although it's never physically dangerous, overdosing can get really uncomfortable. I'd start with 10mg and see how that works. Give it at least 2 - 3 hours to kick in. You will build up tolerance when using it more often, so you could increase dosage overtime. And make sure they know what they're selling when you buy.
The effects are different than when smoking because the THC is processed by your liver which then releases a different chemical compound called 11-hydroxy-THC.
I enjoy it more these days than smoking. It relaxes me. It could help cope with pain too.