I'm going to start out by explaning what different functions in mIRC does, before we begin i assume you know IRC/mIRC commands pretty well, cause this is very usefull.

Variables:
Variables are being used to store information and data. Things can be stored temporary, or by a timer, and it can be set so it's always there.

Popups:
Popups are really good shortcuts for using your mIRC faster if you use your mouse a lot. Popups are the windows that appears when you right click on a nickname, or in a channel or even in the menubar of mIRC.

Aliases:
A very important function is aliases, you can use this to create your own commands. A alias that is by default in mIRC is /j #channel, which will join a channel.
Aliases get called by using the '/' command (if you didn't set it to another character).

Remote:
Remote is where you can make your scripts, react to a certain server event, etc. When a user joins, you send him/her a notice for example.

A question you might ask is, "Where do i put my source?" mIRC has a editor, which allows you to script in mIRC directly so you don't have to have a annoying text editor open, and then save, and load all the time. You can access the mIRC Editor by pressing Alt+R, or by clicking "Tools" from the menubar.

When the mIRC Editor appears, you have the options of tabbing through some of the sections, that i mentioned above, like "Aliases" and "Popups".

You can comment your code by putting either ; or REM in a line
for it self with the text, for example ; this is my comment

So far for the first lesson. In the next lesson we will take a look at popups. Seeya then!