For someone who doesn't really hike what is there to do in the Black Forest and how much time should be allowed.
There are a number of traditional spas in the northern part, including, but not limited to Bad Herrenalb, Bad Liebenzell, Bad Wildbad, Panorama Spa in Freudenstadt. I would plan to spending at least two nights in one of these towns and the day in between in one of the Spas.
There are also a couple of scenic railroad routes through the forest, the most famous of which is the Schwarzwaldbahn, between Hausach and Triberg. The Murg river valley, from Rastatt to Freudenstadt is also scenic.
Right outside of Hausach is the Black Forest open air museum, with examples of houses from all over the Black Forest.
It also depends on where you base yourself. There are many rather flat walks that stay on the same altitude. What makes the Black Forrest rather special is the clean air and that very interesting smell of their air, very unique... If after the walk you eat a bit of Black Forrest ham you'll see it all fits together really well...