Can’t install 98 over NTFS drive

I just inherited a refurbished Dimension for my classroom, and when it started tp boot up, it gave me the message that there was no operationg system. I then used a Win98 boot disk to begin to load one on. After performing Scandisk, I received the message “Can’t create temporary directory. If you have HPFS or NTFS installed on your hard drive, create MS-DOS boot partition to set up Windows.”
How would I go about doing this? A simple format will not work.