Overclocking is not that hard, but I suggest you read quite a bit.
One thing for general PC knowledge I would suggest reading, is Upgrading and Reparing PC's 16 Editiot by Scott Meuler
Than read all the OC'ing sticky's, and you should be set.
EDIT: That book doesnt really deal that much with the upgrading and reparing aspect, it just gives you a large amount of PC hardware knowledge