Registry help needed

Anyone has a good site to learn registry... i want to learn how to create my own icon related to my saved file... when the user click on the saved file(icon), the program will be opened.. just like excel, word.. or others...

and how can we create a folder for our program? like when we install, how can we automatic create a folder for our program to save teh file..

thanks

To create an associated extension, create a key under HKEY_CLASSES_ROOT.

To create a directory, use the MkDir function.

MkDir "MyDirName"

Thanks for the reply..
So, where should i put the codes? i need to make it as installation package... wonder what to do...
please
and again, thanks