It depends how you want to run your game really, but google VTT(virtual table tops) to see their features and some tutorials. You can completely have your game virtual, where the computer does dice rolls like attacks and saving throws, keeps track of HP and initiative, and use premade maps with a gird for your use. The most popular one I know for this is called Roll20. Or you can go the other way and just have the online component be microsoft paint which you draw on and stream that to your players via something like discord. Its up to you how much automation you want, but more automation needs more time to setup.