RPGXP holds all of the answers.
Print out a few different scripts (like Scene_Menu, Sprite_Character, Window_Item) and just read through them in your spare time you're not at the computer. The time you do have at the computer, try reading through similar scripts, and comparing the differences.
Questions? Go to
http://ruby-doc.org/core/ or google 'ruby x' (x being string, array, FileTest, etc)
It's sorta like being a baby again. If you hear (in this case read) this language enough, you learn it, and it almost becomes second nature.
. . . thats by opinion though. Thats how I learned. Couldn't be bothered looking for a tutorial. :D
For the bare-basics, I recomend starting with Scene_Menu. It illustrates things like def, if, case, when, the simple things like that simply, as thats all it is, pretty much.
I'm really not sure though where to look for variable support. I learned from the Net RMXP Online database, so I had a lot of modified stuff. But you do definitely pick up stuff without tutorials, and just by reading.