Do you know any reps? Do you have a ski resume (including competition results, seasonal goals, and filming projects planned...NOT a list of tricks you can do or want to do, companies don't care about that). Are you tight with a shop that might be able to hook you up (shop sponsorships are the best way to get started, you start with a small discount, then maybe can get on a program where you get some skis for a season...but the big goal here is to get into the industry and possibly learn some reps to then bypass the shop). Do you have any marketing experience?
These are a lot of big questions to ask, think about it, I know TONS of skiers out there who are sick, but don't have any sponsors because they're just not worth giving skis to, they want someone who is going to sell skis, that's not necessarily the best skier on the mountain. I've had a few sponsors over the past few years, from small shops to big companies like Line and K2, and I'm not even the best skier at my small hill, but I know how to get people to be interested in buying a certain product. Remember, a sponsorship is basically a job, and at times it can suck (I'm not riding for any sponsors this season except a few small deals that don't require much more work than wearing a tshirt every now and then, I want a break, it takes a lot of the fun out of skiing at times...it is cool to get free stuff, but you're now contractually obligated to do certain things depending on the sponsor/program now). But, since it's a job, you need certain skills, and you are required to do certain things...too many kids just think if they make a sick edit they can get free shit and not have to do anything (not saying that's necessarily what you think, but it's something that needs to be said in general).
Anyways, there is no website you can just get sponsored with, you just need to go out there, get your name known, and take some risks and do some work if you REALLY want a sponsor. Good luck.