if it were me I would simply Google 'Minecraft mod tutorial' and just watch a few vidoes.
Probably not the best idea, due to the update frequency of Minecraft/MCP. It might help you get the general jist of how things work, but I've found that it's more trouble than it's worth.
As to the difficulty of making a mod, I would say it depends heavily on how you want to go about it. You could download the Minecraft Coder Pack (MCP), set it up, and edit the minecraft source directly and have a rudimentary "mod" in a matter of minutes. But it won't be pretty, and it would be of the mod type where you have to insert it directly into the minecraft.jar, which is really not something most people want to do and could easily break compatibility with other mods. I find using Forge to be much better. In fact, if you download the
forge source, it includes the MCP environment and all you have to do is click install.cmd (or install.sh if you're on a mac/linux). It even downloads the jar files for you. Awesome.
As for tutorials, Forge has an excellent
tutorial series that was enormously helpful for me when I wanted to make a few peripherals. I would start there. Well actually, I would start with learning the basics of Java (plenty of tutorials out there on the net), and then going on to Forge tutorials. After that, you can probably dissect the forge javadoc and get anything else you need from that. Also, check out
this for some good references that you might find handy.
Overall, you could be in for a long haul depending on what you want to make. Making new pickaxes/items or adding new blocks is relatively easy - I imagine changing the lighting system would be pretty challenging.
Good luck :)/>
