Basic

A "Hotkey" is simply a key or a combination of keys used to trigger some actions like opening file explorer on windows when we press "WIN+E".
now to create a hot key , all we have to do is -
hotkey :: trigger ;
here , the hotkey (or) key combination goes to the left side of the '::' and the trigger or the event goes to the right side of the '::' .
this works like
if(hotkeypressed)
{
         event;
}
here are a few special keys and their symbols-
WIN key-  #
CTRL key-  ^
ALT key-  !
SHIFT key-  +

So , if i want to open chrome if i press WIN+C ,
#c:: run Chrome
#g:: run C:\Games\Counter-Strike Source\run_css.exe
Or if i want to send a string when i pressed a key combination ,
#m:: send hello world!!
#p:: send my first script

To create and run a script ,
1.Install and run Auto Hot Key from HERE!!!
2.Right click and in the context menu , click on new->auto hot key script

3.Rename the file to desired name , right click on the file , click on edit script( if you want another good text editor with good features and AHK support, use sciTE4AHK)

4.code in the hot key and triggers you want , save the file and double click on the script to run it and you are all done!!.

Here are some Basic Scripts that you can use -
repeated text
key shortcuts