Software development?

I need help here. I have quite an interest in computers, and I've been trying to learn programming languages for the last year or so, and I keep falling over at some point. I'm somewhat familiar with the syntax of C/C++ and a little with bash or QBASIC, most familiar with MS DOS 8 Batch. My problem is that I keep trying to learn too much at once and always fall over at some point, and when I try to focus on just one, I eventually get lost in my learning. I hate to say it, but I need a complete beginners course in this stuff. Before I ask, I'd like to explain what I want to do (don't laugh!). I want to write a computer operating system, starting from scratch. I know I'd be better off if it were based on Linux, so it would probably be that. I know that I'll need to know at least one object-oriented language and embly language, and probably bash scripting. Any suggestions on how to learn what I need to learn?