Join the rootsweb e-mail lists for Arnett, Arnet, or Arnette. Join the ones for the localities where your ancestor may have been in time.Then totally search with genforum, and all kinds of search engines on the internet. Then get with the probate office where your people were located.Eastman's Newsletter used to be a great source for me.Today, there are many, many new sources.
However, I urge you to post here, and on those e-mail lists.. in a way that describes your tree better than.. "Help! me find my family."
Generally, the names and places and earliest dates with a brief lineage description really helps others to know "if" they are connected, or might help you locate your relatives.