Multiple selection query with subcategories

Hello,

I would like to make some sort of a order form, where the client selects what he would like to order.
When he would arrive at the order page, he would have multiple choices, and each choice would open multiple sub-categories, which depend on the first choice. The selected choices would then be sent to me via email or whatever. Also, to be able to include the name, phone, email of the client and various info..
The selection could be done by drop-down menu, or radio-buttons or something different. Please help! 🙂