While it’s a no-no to post recipes verbatim from a cookbook, and best if you’ve made up your own, you can certainly post recipes inspired by other recipes. It seems like a lot of folks find their own voice pretty quickly once they start trying out all of the different recipes on here, and soon want to contribute their own!
Ray is right on here. We wouldn’t want recipes posted verbatim from books without permission. If there is a particular published recipe that you’d like to share, make sure to ask the author first and give them credit for the recipe. Take a look at these recipes for examples of posting published recipes (with permission):