tickover

Hi All names Terry 78 yrs from Plymouth UK. Have just been given a used Laptop by the family [my first attempt at computing] and hope to store my Aircraft photos on it [ one day HI] Its a HP Compaq nx 6110 with win 7, 2gb Ram ,and 37.2gb of memory i am told Now to my problem,Local disk C: with the 37.2 gb is almost full ,it says i have only 9gb free space, there is nothing else on the Laptop,no programs etc , so surely win 7 does not use all the rest of the drive namely 37.2 minus 9 ==28.2gb, or am i looking at it to simply??? i have the win7 disk and key number , do i start again or physically remove the drive and replace? any help much appreciated Regards Terry [tickover]