i think you have a conception that rainmeter is meant to show the date/time on your desktop, when in fact it is meant to display whatever system monitors you configure it to display. but it's got a very steep learning curve, so unless you spend some time with it, you won't be able to set it up yourself.
so yes, just download some skins for it, drop them in the skins folder, and you should be good to go.
another option is samurize, which i actually prefer because it does a much better job of drawing text on the desktop. but it's similarly hard to skin, so you'll have to look around to find something you like that's already been built, and run that.