Click on the DNA button to the right of your name. On the page that appears click on 'DNA tests'. On that page there is a place to enter information about any DNA tests you've taken. Once you've added profiles for your parents and other family members to WikiTree, information about your test will also be displayed on their profiles, as appropriate.
Some previous answers to this type question:
http://www.wikitree.com/g2g/114244/can-i-link-my-d-n-a-test-results-from-ancestry-to-here
