When, for the first time, you log on your 2 stat character with 12 dexterity. Stumble your way down to the bank, after having continiously pestered others to take you, when you finally attempt to explore for yourself, you notice it was only located 4 squares away. You withdraw your 200 gold, so you can buy that nifty rotten piece of wood also referred to as the Oak Staff. Start bashing the Small Snake south of Nightmist with 15 other lvl 1's while occasionally (read: all the time) you scroll South Gate House asking for heal.
That is when you can still get away without using macros. After you've learned some more about the game and notice that with one character you can barely walk to Dedenya. You then open the roller and make a better character. After that the only real skill Nightmist has (the carefully aiming for a picture to click) will be cast aside and in come the macros.
A macro allows you to use certain commands repeatedly. This page will explain how to use them.
With every normal attack, which uses the standard attack button:
the server sends the message /a [monster]. Where [monster] is anything you click (be it a player, monster or an item laying on the ground). Putting that in the macro box after F1 (don't forget to select autosend) and save changes will cause that every time the F1 key gets pressed the message /a [monster] will be send to the server. Example:
by pressing F1
You attacked a Small Snake with an Oak Staff for 6 points of damage.
N.B. The same is done with skills and spells, only instead of /a it will be /cast [skill or spellname]/[monster or player]
/cast create spring/angelus
/cast heal/demonic general