Sorry, but I'm a beginner in ST9, so I do not know how to put a retaining ring on my assembly. Can you show me how I do?
Hello are you referring to which assembly constraints should be used?
Here is a model that uses a retaining ring. It is constrained with a mate to one wall of the groove in the shaft and an axial constraint to the shaft.
If you are using an E-Clip or something that may not have a circular shape, you can always sketch a circle in the clip part itself and use it to locate the clip in the assembly.