I have just started a new save file and would like to set my starter, in this case eevee shiny. How would I be doing this on a computer running Windows 10?
You can’t. You can move around graphics files to make it look shiny but if you want it to actually be shiny you’ll have to go through the slog.
You’d have to reset through a cutscene and a battle with a horrific 1/8196 chance. You could get eevee later on in the friend safari, which is a much easier time. Worst comes to worse, do as Noob said and swap image files or farm IV stones to pay somebody else to hunt for you.