You should choose an easy to type, unique nickname. You will be known on IRC by your nickname, a made-up name that serves as your unique identifier on the network, kind of like an Internet email address. If you try to choose the name of someone else already logged onto a network, the network will reject your choice and ask you to choose a different name. Most IRC applications include a setting to automatically set your nickname at startup.
Because your nickname must be unique, you should choose an unusual name. However, you don’t want it to be too long, or too hard to type. Common guidelines are that it should not be too common, be easy to remember, and not identify your gender or age.
You can set or change your nickname at any time with the /nick command:
/nick piano7
If you wish you can start by choosing any nickname to get you started, such as “aaaa1”, and then, once you gain experience, change it to a better choice (except on DALnet, which assigns a permanent name).