i don't know if you can "be" a humanist, like you can "be" a Christian. My knowledge of Humanism is limited, but a friend passed away recently, he was an atheist, and so he had a humanist funeral.
The 'Celebrant' who led his funeral said that humanists were people who believed in reason, and did not let their lives be ruled by "superstition" and other things that had no proof. She also said that humanists were people who lived life to the full, in the hope that when death finally came, they could feel satifsied that they had lived the best life possible. They look to treat others with the kindness, compassion and respect they deserve. She said that my friend would never be gone as long as we kept his memory alive, and we should not be sad that he had died, but be thankful that he had lived. She didn't mention the anything about heaven, so i can only assume humanists believe death is the end, but as i said, my knowledge of them is limited to this one experience. It all made sense to me though.