How to register an IRC-Nickname

mIRC
1.Go to File, Select Server, Options, Perform
2.Go to Network, click Add, find 'freenode' in the list and click OK.
3.In the Perform Commands section, add:
/nick nickname_you_want
/msg nickserv identify yourpassword
4.Click OK as many times as you need to get out of the menus and you're all done.
ChatZilla
1.Go to ChatZilla, Select Preferences.
2.Click Add and add a server with these settings:
Type: Channel
Network: irc.freenode.net
Target: One of the channels from the list below.
3.Highlight the Network name (irc.freenode.net) and select the Lists tab.
4.In the Auto-perform commands section, add:
/nick nickname_you_want
/msg nickserv identify yourpassword
5.Click OK to get out of the ChatZilla Preferences notebook dialog and you're all done.