I made ganache for the first time yesterday. Now that it has set, instead of making truffles, I'd like to cover a cake with it. Can I just melt the chocolate again then pour it over the cake? Please help.

Yes. Warm it very gently over barely simmering (or just hot) water. Try not to beat it-that incorporates bubbles which can mar the smooth surface.

JoAnn B. thanks so much for the response