How to remove the hard drive from Inspiron 4100?

My laptop is very old. And recently when I open it, some error message come out, said"Primary hard drive 0 found", then cannot log into operation system. But sometimes primary hard drive is found and can log into windows. I thought the hard drive goes to die, and I'd like to change one. But I don't know how to remove and replace the hard drive. Anybody can help me? Thank you very much!