Do oyu charge me for taking on a regular size backpack ??

what bags can I board the plane with ? that you don't charge me for ??

do you charge me for bringing ANYTHING on the plane ??

I just have a little small bag on me.

Will you charge me or not ? I did not declare it because it is regular size.

We don't charge you for anything.

You may carry, free of charge, one cabin baggage :

Strictly one item of cabin baggage per passenger (excluding infants) weighing up to 10kg with maximum dimensions of 55cm x 40cm x 20cm is permitted. (handbag, briefcase, laptop, shop purchases, camera etc.) must be carried in your 1 permitted piece of cabin baggage.

Regulations about what you may carry in your cabin baggage :
http://www.ryanair.com/en/questions/cabin-baggage-allowance

EU/EEA cabin baggage security restrictions require that passenger cabin baggage containing any liquids, gels, pastes, lotions or liquid cosmetics MUST be presented at the airport passenger security point in a transparent re-sealable bag of no more than one litre capacity (e.g. 20cm x 20cm ziplock freezer bag). Only gels, pastes, lotions and liquid cosmetics in containers of 100mls or less will be permitted through the passenger security screening points at all EU/EEA Airports, please note there is a limit of one transparent resealable plastic bag per person.