[TYPO3-dev] How could I create services in 6.x

[Jose Cuenca]

Hello, I'm new in TYPO3 and I'd like to make an authentication service. (I want to ask to PWM if the account is expired before login, I think that the service is the best option)
I'd read that I can't make "Services" with Extension Builder. 
How could I do it TYPO3 6.x?

I've read that I could see in TER but those Extensions are vey big and I don't know wich folders and files  are necesary.
Please help me!


Thank you very much