I need money soon!! what do i do?

i want horse riding lessons. badly. but i dont have enough money. the lessons would start over the summer. so in about 3 months. ive got about 110 dollers but i need at least 500-700. im a 13 year old girl. and i work at bridal shows with my mom... maybe 2 times a month and get 10 dollers each show. but some months there are 4 and some there are none. so that isnt very dependable. but what else could i do to make some profit? please help!!!!!