Dress casually but nicely, bring a sweater or windbreaker for changes in the weather. You can expcet a lot of big-wigs to be in the tent. There will be a very nicely catered buffet and, if not an open bar, at least a cash bar. Sometimes the higher-ups in a corporation use this occasion to see how much their employees drink. I went to scads of these while working for Chevrolet (only ours were at Marlboro Series auto racing events).
Be prepared to do a lot of hand shaking. Have breath mints in your pocket and try to eat lightly, often, rather than load up your plate and sit center stage stuffing your face. Extremely lasting impressions are made on people with a great deal of influence on your future at these events. Watch your step but be relaxed. This is sometimes the only fun the executives make time for all year long.
You should have a great time. The food will be incredible!
