Well I was just reading on arrl.org and I saw some very interesting things to do for field day. They are totally great and you should put them on your facebook twitter and websites, so word the spreads! that is basically what I am doing here!
So basically you should just try and get people to come to your local field day and participate in it. There are tons of matarials that the ARRL supplies you with. To read the post go here. for a nice flash logo, maybe for websites go here. there is also a lot of info on that page as well! So I hope that you will like to promote field day as much as I do!
To find a field day near you please check out this site