This is really not a very difficult process, and doesn't really take that long to do. Can take slightly longer if there are fit problems or adapters are needed. Make sure that the floppy cable will reach the drive in its intended location. Refer to the system layout planning procedure if necessary. Make sure that a power cable from the power supply will reach the drive.
Adapters are available for a couple of bucks for use in older systems.
Make sure that you don't mount the drive upside-down. The system case should be open before you begin. For instructions on opening the case, refer to this procedure . Some cheap cases are made from very flimsy sheet metal and may require you to flex them somewhat to get the drive to slide in properly. You'll need to know where pin 1 is when you connect the drive up, which may be quite a while later on.