hey Im 16 but I got my job when I was 15, working in a card and gift shop.
Do you mean a saturday job?
You should be able to get a saturday job in most shops, some wont employ under 16s but they are in the minority.
You generally dont get paid to work in a charity shop or for volunteer work.
You should just go round the shops in your local area, and ask to speak to the manager then say you are looking for a saturday job and do they need anyone. Or you could write to these places.
Hope this helps xx