Dillman Family Association has a project on FamilyTreeDNA.com. This project is for Dillman males who have taken a YDNA test at FamilyTreeDNA. Our project administrator is Andrew Stillman. You will want to take (at a minimum) the 37-marker test, but more markers is better, and the Big-Y700 is preferred if you can afford to take it. Once you have your YDNA results, visit the Projects section of the FTDNA website by clicking on the Group Projects link in the top toolbar and Join A Project beneath that. FTDNA may recommend some projects for you to join, and you can search by surname.
We welcome you to the project! Genetic genealogy has proven to be an excellent companion to traditional paper genealogy, and has proven (and disproven!) many family lines. Let us know when you join here as well!