Rachael: I solved the problem by getting one of these (and there are MANY more models on Amazon)
I would buy a used one and work on adapting it to my decor.
If you want a gas or wood burning one, then you’re talking about a non-DIY project, as you’ll need a chimney or a proper fireplace flue, a hearth and fire proof materials 18-24” around the firebox.
If you are planning to build a higher place that is not functioning start by looking at Facebook marketplace or craigslist for mantle’s people. When she find a mantle against the wall and then go fine feeling stick tiles to go around inside.
If it's a wood burning fireplace you'll have to check on the code for your area. You may need permits for that