Hi, I'm having a lot of fun with this game but still don't really understand the whole guilds thing. I'm currently level 37 and have 22 shown as free. So I take it that for every race level I progress I have a guild level open. I'm just not sure which guilds I should be trying to join or how I find them / join them. Any advice would be appreciated.

This is explained in help getting started but I will give fast explanation.

Each player level gives 1 guild level.

level 1-10 go to background.
level 11-15 go to race guild.
level 16-100 go to real guilds.

Real guilds you can join depend on background. Help open guilds.

So player levels are mainly a way to get guild levels as they are the important things as guilds provide all skills and spells. Ok at start player levels give massive stat boosts but that lessens after lvl 30.

Ask more on newbie channel.

Well, you're correct about the free levels part, you can now use those 22 levels on a real guild.
You can choose from whichever guild is open to you background. Some useful commands to try out:
- help free levels, help level, help open guilds, help <guildname>
- show guilds (to see your background)

Also, to get answers more quickly try the newbie channel, it's pretty good for getting help.