The Nokia 5233 supports a official maximum memory card size of up to 16 GB. The type of memory card that the phone supports is 'Micro SD'. It is possible to insert a 32 GB Micro SD memory card, but the phone will become really slow to use and will hang often. When choosing a Micro SD memory card, ensure that you choose a good manufacturer like Sandisk or Kingston. Cheap unbranded memory cards have very poor performance and stop working after awhile.
1) Power off your mobile phone before proceeding any further. This is because you don't want to corrupt the data on the memory card.
2) Turn the phone upside down and remove the back battery cover. The best way to do this is to insert your finger nail at the bottom grove and gradually pull it off.
3) Once you have removed the rear battery cover, you will see a Micro SD slot located on the top right hand side.
4) Obtain your Micro SD memory card and carefully insert it into the Micro SD slot on the handset. Be careful not to put in the wrong way round or push it in forcefully. This is because it will either become stuck or will snap, so handle it with extreme care.
5) If the Micro SD memory card is inserted correctly in the slot, you will hear a click sound and it will lock in place. Now all you have to do is refit the battery cover you remove earlier on.