Combo box help

I have two combo boxes, and once a selection is made in the first one, I want the second one to be filled with the appropriate information. Can someone point me in the right direction. I don't know where to start. Thanks.

Take a look at the ComboBox Click event (this will let you know when an item has been selected). I also recommend that you set the Style property for your ComboBoxes to 2 (Dropdown List) so that users can only select items from the list and not type their own text.
Once the user has selected an item, you can clear the second ComboBox using the Clear method, the add new items in a loop using the AddItem method.
Depending on the type of data you are presenting, you may want to also look at the ItemData property. It allows you to assign unique numbers to Combo items which is great for comparing ComboList items to database rows (among other things).