This is a detailed tutorial for setting up mIRC and adding a server/channel. It's very basic as it's intended for people who have never used the program before and know nothing about it.
Step 1. Downloading and running the software:
The software is available on the official site
here. It's very easy to install, so I'll skip that step.
So now you have the program installed and running. The first thing you see when you run mIRC is the status window. It displays all the 'status' information and is the place where you register your nickname and so on. You can also use it to join a chatroom, but more on that later. The first thing to do is choosing a nickname. There's a small yellow icon made of a folder and a hammer. If you click on it, it takes you to the Options window. Just fill out the fields with the appropriate info. You don't have to provide your real name or an email adress if you don't want to.
Step 2. Adding servers/chatrooms:
Next step is adding a server, which is a simple procedure. While you're in the Options window, click on "Servers" in the Category menu and then on the "Add" button. A window pops up. Fill out a description of the server you're adding (I just write the name of the server i.e. "Scifi") and then add the actual irc address (irc.scifi.com) where it says "IRC server." The port is set by default, you don't need to change it. And I usually leave the Group and Password fields blank. Click on "Add" and you're done! You can now go back to the "Connect" category and choose the server you just added from the drop-down menu.
You can go ahead and connect (the yellow lightning icon is a connect/disconnect button). Once the information stops scrolling, you can type /join #channelnamehere and hit enter, and that will automatically take you to the chatroom. You can also join a channel (and save it) by clicking on the favorites folder, which is right next to the Options icons. Type the name of the channel, hit add and it will be saved in your favorites folder. Feel free to delete the existing channels if you don't need them ;)
Registering your nickname:
As far as I know, not a lot of people use this feature, but registering your nickname will prevent other people from using it. To register your nickname, just type the follow line in the status window:
/msg nickserv register password emailaddress
Enter a password and your email address, obviously. An authentication code will be emailed to you. Once you get it, which should be instantly, enter it in the server window and hit enter. And voila, your nickname is registered. From now on, everytime you log on to that server, you will be asked to identify your nick. Just type the following:
/msg nickserv identify password
And that's it. The whole thing from installation to joining a chatroom takes less than 5 minutes, really. If you have any questions, feel free to post them here!