Hi Carolyn,
WikiTree requires that living individuals enter their own DNA test info here.
If you have a brother that is still living, he will need to join WikiTree at least as a Family Member to add his own DNA test info.
If you have a brother that is deceased, and you manage both his profile here and his DNA test results, you can enter his DNA results on his profile. On your deceased brother's profile, go to the drop-down menu for his profile-ID and choose DNA then DNA Tests.