Do I need to contribute before I request money?

The short answer is no. 

Kin is not a crowdfunder but you can set up a group because you need something right now and a lot of traditional rotating funds begin this way. Remember Kin Cooperative is for mutual aid, that means saving together should benefit everyone in your group over time in the way that you have all agreed together. 

It's fine to contact your friends and say I have an emergency that I can't afford but if we all chip in and keep putting in the same amount every month, then I'll have paid everyone back and we'll all have benefitted. For example: 

Tabi needs a new washing machine because her old one broke. She can't afford the £400 for a new one but she's got 7 friends and if all 8 of them together (Tabi + 7) put in £50, that's £400 (50x8). Tabi's friends agree to pay in £50 every month for 8 months. Tabi requests £400 the first month and buys her washing maching. Next month, they each pay in again and one of the friends requests £400. They repeat it every month until all of the friends have received £400. Tabi has now paid in £50 x 8 months = £400, the price of her washing machine.