You will need to load the drivers from the Dell website, yes they still have drivers for your computer running Windows 98. If you have another computer with a CD burner it may be easier to make up the driver install disk to a cd disk. Windows 98 will not access usb pendrives without drivers loaded.
The Dell drivers when downloaded are Zip files which self extract to a folder called R then a number. to make then meaningful rename the folders as Chipset, Network, etc
Start with the Intel 800 Series Integrated Chipset driver then the Video adapter Intel 810 Series Integrated Video, then Audio Analog Devices AD1881 Integrated Audio
Your computer had the option of 3 different network adaptersf you will need to get the number off the chip. Attached is a picture of the part of the motherboard with the chip
The drivers are available here
https://www.dell.com/support/home/en-nz/product-support/product/optiplex-gx110/drivers