Well, I'm sure this great website will help you find a detailed guide, but in short, this is it:
If this is your first time on the sythe irc, enter all these commands...
/server irc.sythe.org
/nick YOURUSERNAME
/ns register PASSWORD EMAIL
Now check your email and follow the directions...
Finally, /j #sythe to get going.
If this is not your first time:
/server irc.sythe.org
/nick YOURUSERNAME
/ns identify PASSWORD
/j #sythe