hmm, OK thats not a problem if you dont have bootdisk, do you have floppy drive?
and download the boot disk image from there, DOS 5, DOS 6.
when downloaded, on clicking it will ask you to insert blank floppy drive. and it will copy whole bootable image + few more files that are important in formatting and else on floppy.
boot your ssytem with that floppy, and once A: comes, go into B: (as then B: will be your floppy drive)
locate the command Format there, and format your Hard Drive, writing command format c:
that will foramt your hard drive on FAT32 system, and you can instal win98/ME.