First of all, this is probably the wrong thread to ask that question. However, since I'd imagine that this is a somewhat urgent matter (it is Week 1 and all), I'll give you a few tips:
- Make, find, and use connections. If a team member's parent owns a business, try to have them sponsor you. Your mentors' places of work may also be willing to help out.
- Have a standard(ish) paragraph that you send to potential sponsors. This will keep your message consistent, as well as lessening the chance that you'll misrepresent FIRST or your team in a hastily dashed off email.
- Go to tech industry conferences (though other business conferences could also work). The people there are usually attached to decently sized corporations, and if they see your robot and/or program and think that it's cool they'll be more likely to sponsor you than if you just cold-called them.
- Talk to other teams in your area. A quick look at the Midwest Regional (the one you're going to) shows that 54 teams are currently registered. All of them have sponsors and most of them have years of experience in FRC. Some of the better teams there include 71, 111, and 1675. Talk to them -- you never know what could come of it.***
*** Making friends with really good teams never hurts, either.