CDR...blank disk that can be written on once and cannot be over written. CDRW....blank disk onto which information can be written and deleted and re-written (like a floppy but 450x more capacity.) To write them you need a CDRW unit (I use LiteOn) which will cost around £35 for an internal and £70ish for an external usb one. The unit will come with Nero or easy CD software which will make writing the disks easy (drag n'drop).
The disks will hold around 700Mb of info and should last about 20+ years. 100 CDR (write once) disks can be bought for around 20 squid if you trawl the usual suspects on the net. CDRW (write and over-write) disks are more expensive...around 10 for a fiver.
CDR and CDRW disks should be able to be read by any computer or modernish music system.