Fitting 2 histograms to a third one

Hi,

I want to fit two non-parametrized histograms (like signal and background) instead of two functions to my data histogram.
One told me that this is easily done in paw.

So I think it should be possible in RooT as well.
But I can’t find anything about it in the manual.
Please can anybody tell me how to do that.

Greetings
Roger

See an example in tutorial fithist.C

Rene