For Nokia E52, you can have the options to transfer contacts from SIM memory to phone memory or vice versa. To do this, Go to Contacts>Options>Mark>Mark All>Options>Copy>Phone memory or SIM memory.
You can also copy contacts individually: Contacts>Select the contact you want to copy>Options>Copy>Select memory where you want to save it.
If you intend to save contacts to your SIM card, please take note that number of contacts that can be saved depends on the SIM card. For phone memory, it will depend on the available memory on the phone.
For backing up your data, you may use Nokia Suite. For instructions, please refer here.