40 Gig hard drive but only 2 Gig shows

Help! I have a Seagate 40 hard drive, it had windows 2000 on it and that crashed, I had to format C it and since I didn’t like 2000 I put 98 Second E. on it. Now it only says that I have 2 gigs and half is eaten up with all the windows bloatware I have on it. How do I get the other 38 gigs back.
Thanks