Google map markers

Looks like this is oldish so hope this is still helpful to you:

You will probably want to store your data as a post with postmeta entries as well. So you are going to have to allow visitors to add data in the same way your plugin is storing it. There are some plugins out there that do this both with and without a google map. If you are looking to build something from scratch you could take a look at what others have done and use that as a starting point. Otherwise if you are looking for quick solution I’d take a look at a couple of plugins and pick one. You can start by taking a look though the plugin directory on wordpress.org. https://wordpress.org/plugins/

–AJ