List of assemblies can be found in SSMS under [Database]/Programmability/Assemblies. You can right-click and generate CREATE script or else.

Also, you can "select * from sys.assemblies" to see all registered assemblies in database.

What do you mean by "view the code for the created assembly in sql server"?

You cannot see the code itself, as assembly is compiled into DLL and code is not placed into SQL server itself, registration of assembly creates the reference to DLL - that's it.