I have a requirement to open standard shopping cart create screen in NWBC from a custom webdynpro component and pass the items details from the custom component to the standard shopping cart screen and create items.
Could you please provide me the steps to achieve this?
First I recommend you to create a trace in ST12 about the standard SC create process to check the callstack how it is working, then you can get some ideas how you should call the standard hopping cart screen from the custom webdynpro component.
You can check the following SAP Note how to use ST12:
2436955 - Step by step instructions on how to use ST12 trace for analysis