Auto Responder Email from Picklist form fill

Is there a resource that I can view that will explain Picklists down to the finest detail? I want to be able to send a specific email based on a users response from a drop-down picklist. How do I set up the emails, campaigns, etc. I have created a picklist, but I have no idea how it talks internally in Eloqua to choose the email I want it to send.

Any help is appreciated!