Jquery newbie needs dead simple ajax example

I don’t know jQuery and I don’t know Ajax. The Select2 Ajax example looks impressive but so far, I haven’t been able to recreate something like it - this is another page full of too much great material and options and documentations but what I would need to start as a beginner is a dead simple example without any bells and whistles, just a complete html + script page with an input field with a dropdown and autocomplete, getting some example values from some remote ajax source (also showing what those data should look like). Maybe such an example exists already?