How can I install a theme

I am using dw Question Answer and I tried to use dw wall. But dw wall shows posts on front page and the wordpress categories not the categories I made in DW Question Answer. I would like it to show questions from all categories on the main page and also by category. And in the categories in the sidebar I want to see the DW QA cateogries. 😀 Is there a way??
Thanks!