If you are looking to automatically send a "Thank you" message once a customer has registered to receive information from you. You are even able to send a sequence of emails if you would like to.
All you will need to do is create an automated campaign and then link it to your Web Form by selecting under Step 7 - Automated Campaign Options the relevant one from the drop down list.
Then once you have save the form and started the campaign depending on the sequence you have set an email will be sent to your customers.
Here are come further documents which you might find useful: