your username is invalid. connect with your real username in lowercase."
I had to uninstall/reinstall mirc. even though I am using the same info, I get this error. I am a new user and I am a bit confused.

What you need to do is explained in the message.

Whatever you are using for your username (also called your ident) has to be in lowercase

If you are using SteveO as your username, you have to make it steveo