This MAY be one of the common problems around here. Is the problem that you connect the Iomega External Hard Drive to your computer and it is NOT seen in "My Computer"? If that is your problem, almost always it is because you must do a two-step process to prepare the drive for use by Windows. They are to Create a Partition on the drive, and then to Format that Partition. Until those are done, Windows cannot recognize and use the device, even though it is present as hardware. Some systems combine these two and call them together a Disk Initialization process.
You can do these yourself by using Windows Disk Management. It is part of Windows, and you use the LOWER RIGHT pane of the Disk Management window to do this. However, to make these things even easier, many hard drive makers will give you for free a utility program that does the work. It may be on a CD that came with your Iomega unit. Or you may be able to download it from the Iomega website.