See the column on the right hand side? (or the ads below if on a mobile device?)
These 400 by 400 pixel graphics are the size of your display ad. They will be set up to link directly to your website with a simple click. We recommend JPEG files. In terms of ad placement, you would purchase space per page. For example, if you wanted to purchase space on the Conference Schedule page, you would send us your file and your ad would be placed on that page and would not move from its order on the page. We would send you a PayPal invoice after your ad is published: you are free to pay through PayPal, an over the phone payment (call our office phone), or by check (see our office address below).