Where do you buy backgrounds from I've only seen to in the Toca shop and I don't have tokens and I'm not that far in this website

Trades>Trade Broker>Type dropdown> Avatar Background

Most background, like all types of avatar items, can be dropped by bosses or avalable in games/festival shops. Outside of festivals, the best way to get those would be to look through item sales and the trade broaker to find somthing interesting. I would highly advise you to wait until the 14th as the next festival is about to start and you will probably get a chance to drop/buy some with tokens. ^-^