It provides some information on how to interface with the GPIO pins with a multitude of programming languages. Granted it may not be an absolute beginner guide, it still has a lot of useful information. If I can find another guide I'll comment back here.
I'd also want to echo something that the other reply to your comment mentioned, which is that you should seriously consider starting with an Arduino if you want to do some lower-level programming/interfacing with hardware. From my personal experience, there's a little more documentation on that sort of thing with Arduino than the Raspberry Pi. Additionally, the Raspberry Pi's GPIO pins are not fault tolerant, which means you could damage your Pi if you wire up your hardware improperly. If I remember correctly, Arduinos typically have some voltage fault tolerance (at least there are variants which do), and even if you fry the actual microcontroller chip on the board, it can be removed and replaced for a couple of dollars.
Once you've got some experience on an Arduino board, then I'd recommend doing some of the low-level stuff on the Raspberry Pi.
http://elinux.org/RPi_Low-level_peripherals
It provides some information on how to interface with the GPIO pins with a multitude of programming languages. Granted it may not be an absolute beginner guide, it still has a lot of useful information. If I can find another guide I'll comment back here.
I'd also want to echo something that the other reply to your comment mentioned, which is that you should seriously consider starting with an Arduino if you want to do some lower-level programming/interfacing with hardware. From my personal experience, there's a little more documentation on that sort of thing with Arduino than the Raspberry Pi. Additionally, the Raspberry Pi's GPIO pins are not fault tolerant, which means you could damage your Pi if you wire up your hardware improperly. If I remember correctly, Arduinos typically have some voltage fault tolerance (at least there are variants which do), and even if you fry the actual microcontroller chip on the board, it can be removed and replaced for a couple of dollars. Once you've got some experience on an Arduino board, then I'd recommend doing some of the low-level stuff on the Raspberry Pi.