[TYPO3] Add new clasas file to extension

[Hraklis Karvasonis]

Hi.

I have created an extension that has the default class 
class.tx_myextension_pi1.php with which i can use some insert queries.

I would like to have another class within the extension, for example 
class.tx_myextension_newclass.php with which i will also be able to us 
esome insert queries.

Which files do i have to change and how, so that i will be able in the 
new class to write an insert query into the database like i do in the 
extension's original class?

Any document that describes exactly how i can do this will be really 
appreciated.

Thanks a lot.

Hraklis Karvasonis.