I am not going to comment on the background of how to start webmapping as the other posts from the other users will be perfect for your needs. However, If you require a map that you click a country and an image pop up you can take a look at the Mapbox example for Linking to External Data

You can learn how the code interacts in JSFiddle for the project

If you require more documentation on Mapbox you can take a read of their Mapbox Guides or dive into the code a bit more using the Examples section

If you require a map that you click a country and an image pop up you can take a look at the Mapbox example for Linking to External Data

You can learn how the code interacts in JSFiddle for the project

If you require more documentation on Mapbox you can take a read of their Mapbox Guides or dive into the code a bit more using the Examples section