The instructions for DNA confirmation, and sample citations for matches, are available on the Help:DNA confirmation page, here: https://www.wikitree.com/wiki/Help:DNA_Confirmation
If you have any questions, please ask.
To build on what Harry wrote, you can’t add the DNA of a living person. Living people have to join WikiTree and select which DNA test they have taken. This is because of GDPR https://isogg.org/wiki/General_Data_Protection_Regulation