I'm interested in creating maps and map "mashups" online, and have been pointed to Leaflet as a great tool to help me do what I want.
Leaflet's documentation is clear and easy to follow, but it demands pre-existing knowledge of how to use tools like CloudMade. For instance, Leaflet documentation starts by telling the user something like:
// initialize the map on the "map" div with a given center and zoom
var map = L.map('map', {
center: [51.505, -0.09],
zoom: 13
});
Which I sort of understand, but I don't know how to get the map, point to the map, create the map, etc. There seems to be a huge "how to make maps work on Web sites" chunk of knowledge that's required before diving into Leaflet.
CloudMade also throws you in at the very deep end.
Where do I pick up the Maps 101 knowledge I need to make sense of how all this works?
I assume you were following the Quick-Start Tutorial on Leaflet's website? You can look at the source of the example for the full break down on how it works internally. Leaflet doesn't use any Cloudmade specific stuff other than itself, so you shouldn't have to refer to the Cloudmade tool.
If you're looking for some basic Javascript tutorials (the language that Leaflet uses), there are some mentioned on Language Books/Tutorials for Popular Languages.