I'm a total newbie here and I fundamentally wondered why it is important to have a powerful GPU for the hashing. I didn't totally get the hashing procedure as well but i can read the wiki for it. Since i didn't find any information on this basic level I would appreciate any hint to get a better understanding of the whole systematic procedure.
BTW: Do I have any chance to at least generate one bitcoin with my Apple MacBook Pro? I'm already getting a bit frustrated because there is no effect after hours
Hashing generates a 256 bit pseudo-random integer from the contents of a block. A part of the block, called a "nonce", can be varied each time this is done. A legal block will have a hash which is less than a specified 256 bit integer, called the "target." By making the target sufficiently small, the average CPU/GPU time required to generate a block can be made arbitrarily large. The target is periodically reset, so that blocks, on the average, are generated approximately every 10 minutes. The blocks are hashed into a chain, so that rewriting a block that is followed by other blocks would be computationally infeasible if there are more than a few blocks after it.
GPUs are important, because they are specialized processors with lots of cores. A GPU can execute many Tera-Ops, whereas a CISC CPU can only execute many Giga-Ops. Because Bitcoin mining is dominated by GPU power, it would take years before you could generate coins on your MacBook Pro CPU.