Hi, still haven't found a freelancer? I can do this fast, it's easy.
You just need to have path to a file coded additionally in your web page script and loaded&overlaid over your existing map, right?
Just provide me your current code and the shape file and you'll receive adjusted code back with a demo on my private web server.
I'm Matt Sergei (do call me Matt, please) and 26 years a webmaster and developer, scripting web maps more extensively in last 7+ years mainly with Leaflet and D3.js.
Regards and hope you're safe,
Matt