Backing up hard drive

Sorry for the basic questions, but I have had a message saying that the hard drive is about to fail and I need to back up documents, photos etc. Is there a quick way to do this? Should I buy a portable hard disk and, if so, is there an easy way to transfer my files? I live in Spain, so anything I buy may only have instructions in Spanish (though usually several languages are given) and I really don't want to lose everything. I have started transferring individual files to a USB, but this is time-consuming and I don't want to risk missing something! Presumably as I have a monitor and keyboard I can get away with buying a new hard disk or, as the PC is nearly 5 years´old, am I better buying a totally new set-up?

Thanks for your help.