Monitors are simple devices when it comes to IT. The most common issues when troubleshooting monitors is reseating or replacing the different cables. Default cables are VGA, but nowadays many monitors use Display ports, DVI-D cables, and even HDMI cables.
There are a couple things to note when you want to have multiple monitor setups though
First, determine if the computer has an added video card. Most computers will have what is called an “Integrated” video card which just means the card is fused into the motherboard so it will come with a couple ports for monitors.
Most computers will have both integrated and an add-on card installed in one of the PCI slots. The problem with this, at least in my experience, is the computer will only allow you to use one or the other but not both. If it has a video card, it will disable on-board and will not even let you boot unless you have a video cable plugged into the add-on card. To get past this, you have enter the system BIOS and see if there is an option to enable both at once.
With the push of USB 3.0 ports available, I have found it easier these days to purchase a device such as this. Most of our computers are standardized Dell Optiplex desktops with one VGA and one display port available. With an adapter such as the one mentioned, you don’t have to configure anything in the BIOS and can have 4+ monitors attached at the same time!