If you look at the call I showed you, it returns back a list of artists, and each artist has an array of images. If you're using it with jQuery, your code might look something like:
$.getJSON('http://developer.echonest.com/api/v4/artist/search',
{api_key:"YOUR API KEY", bucket:"images",
name:"Jimmy"}).then(function(data){
for(var i=0;i<data.response.artists.length;++i){
var artist = data.response.artists[i];
//Do something to render out the artist here.
}
})
Inside the loop, artist.name will be the artist name, artist.id will be their Echo Nest id, and artist.images will be an array (potentially of length 0) of images for that artist.