Help w/ Digital download feature for web site

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Looking for help to set up digital download feature on my Long Enterprises.com VW transaxle specialists website which is hoisted @ sonic. Built w/ FrontPage years ago, my site is quite dated. I understand a Wordpress plugin might be the way to go to include this capability. Would like to find somebody who understands Frontpage and Wordpress that could help me with this. Any suggestions or recommendations would be very much appreciated.