There aren't a lot of monero based sites around, and I think there is a lot of opportunity, but I don't really know much about implementing crytocurrency into a website. I figured I might try to start by creating a wallet site, but I wanted to ask if anyone could provide any insight onto the difficulty of that? I may be way in over my head but I'm not sure.
It would be moderately easy to get a working wallet site provided you know some basic programming (python, php, node.js) and a little about web server usage (linux!).
You just need to run a full node on your server, create a wallet, then write some code which checks for payments, makes payments etc. See wallet-RPC for some guidance on this.
As already mentioned, the challenge here would be to implement these things securely/reliably. Making something like this for public use is not recommended unless you know exactly what you are doing. Just imagine if all your users monero was stolen or lost - you'll certainly end up in hot water.
You're right though that there is a lot of opportunity in this space. I encourage you to at least experiment with your idea (i.e get a full node working on your server and programmatically check your balance). Its the best way to learn and from there you'll have a better feeling of what you can do with this technology.