First, you add your DNA results to your own profile. It will be propagated up your ancestors to Joseph Gotobed overnight. For this to happen you must have profiles of your ancestors back to Joseph on WikiTree.
While you are getting those profiles set up (assuming they aren't already on WikiTree) then you can add your DNA to yourself by using the pull-down menu (it's the 2nd from left under your ID) to click on DNA. Then click on the tab that says DNA Tests and add your details for whichever test you took.