To use nonlinear regression, you need to choose a model. In many cases, especially if you are fitting pharmacological or physiological data, you can choose one of Prism's built-in models described here.
•Receptor binding - Key concepts
•Receptor binding - Saturation binding
•Receptor binding - Competitive binding
•Enzyme kinetics -- Key concepts
•Enzyme kinetics - Subtrate vs. velocity
•Enzyme kinetics -- Inhibition