You won't need a splitter / connector. If you have 2 ports right now it's fine.
All you have to do is go to your monitor settings on windows and set the primary and secondary monitor in the right order. Then on the second monitor you just click on 'extend desktop to this monitor'.
Then you're fine. Just plug the other monitor in and you're good to go. You'll need to configure it to be either a copy of your primary display or an extended display in either the control panel > display options, or your gpu control panel.
You don't need any connectors or adapters or anything.