Usually Windows 98 CDs are not bootable.
You need a boot floppy to start the PC
with CD-ROM support, put the Win98 CD in the drive and run SETUP from E: (the CD drive).
If you don't have a boot floppy download the Win98 OEM version here:
http://www.bootdisk.com/bootdisk.htm
Of course you need a working PC with floppy drive and internet access.
After downloading, put a freshly formatted floppy in the drive and run the downloaded file.
This will start the process and create a boot floppy.
Use it to start the PC.
Good luck.
Zee