Bread and using a proofer
The bread proofer machine serves mainly one purpose:

Keeping a choosen temperature.

This comes to play whenever you want to let yeast grow and multiply. Yeast can develop at very different temperature ranges, from fridge to warm room. But "cosy &amp; warm" is usually the temperature where it's most active.

The most obvious use is:


proofing dough, both during bulk and final rise


But looking closely there are other yeast-related uses:


refreshing sourdough
brewing (don't ask me for details here!)


And even non-yeast uses like


making yoghurt


Now, you are asking for a sourdough bread. I won't give you a fixed recipe, but encourage you to choose something nice from the vast realms of the WWW. Try The Fresh Loaf, Wild Yeast or whatever strikes your fancy. I'd assume a Sourdough bread to be made with - obviously - sourdough. But that doesn't exclude yeast, some recipes use both. 

The main differences are that sourdough (which contains yeasts and strains of lactobacillus in symbiosis) is more the slow-and-steady type of dough with rather long rising times (as in hours up to days) whereas pure yeast-based dough may be ready to bake after only one to two hours or so. (But there are yeast-only recipes like baguette which take days of proofing  in the fridge.)

Choose a simple recipe to start and use your proofing machine whenever the recipe says something along the lines of "let dough rise in a warm place / oven with pilot light / ... for X time / until doubled in bulk. 

Remember: When you start baking, it's a good idea to follow the instructions, note what you didn't like and work from there. Perhaps you'll be back here with a more specific question after a few trial-and-error runs - we'll be happy to answer again. And: Have fun!