s30 in phone memory problem

Hi I just got my s30 and I love it but today I got a message when using the internet saying I was low on memory and when I checked it I was down to 2mb but barely any of my memory card has been used and I can't figure out what is using all the in phone memory.  I haven't downloaded any apps just added some photos and ring tones.  When I delete messages it doesn't help either. 

How do I know what is being saved to my memory card and what is saved to my phone and is there any way to control this or fix this problem.  I'm really sad about this