You'll need the original or a certified copy of your marriage license to get started (if you need to request one in Benton County, here's the link). Usually, people begin by changing their name on their social security card and their driver's license. Then it's just a matter of updating your name everywhere else. Here's a nice short guide to the steps involved: www.theknot.com/content/name-change-101.
There are services you can pay to do most of the legwork for you as well. One of those is mentioned in the article linked to above.
