installing 2nd harddrive

hey there, i installed a 40 gig harddrive to my allready there 4.3 gig harddrive. But when i go to the d: drive it says i only have 503 mb instead of 40 gigs. I tried to convert the fat16 to fat32 but it said it was too small and didnt let me..i also went to the emachines manufacturers website to check for a bios upgrade but they didnt seem to have any. Can you tell me why and how im able to fix this..

Thank you