Creating a SSRS Form Letter based on a Data Query

I have done LOTS of SSRS Data Extract Reports...but this is the first time I have ever been requested to create a form letter and substitute data into a form letter that will be mailed out to a group of members within our database.

Can someone provide me a link, be it YouTube or other, that kind of walks me through this process? SSRS Form Letters 101...just want to make sure I follow protocol and standard as to go about doing this. Do I create a SSRS Dataset...SQL Server Stored Procedure to get the result set? How do I apply the data elements to the letter?

Any help is greatly appreciated.

Thanks for your review and am hopeful for a reply.

Thanks!