You buy an external drive that plugs into your USB2.0 and reads and writes DVDs and CDROMs.
Various manufacturers, but Iomega is just one possible source. In terms of high street stores that sell them ,try Maplin Electronics.
Probably less than �50.
Before thinking about getting an external burner check that laptop has USB2 ports, I have a latitude C640 and it's only got USB1 ports and they wouldn't be fast enough for a CD burner.
The easiest option would be to simply buy a replacement drive to go into the modular bay that the current drive is in. (there is a little catch underneath that you slide to one side and the drive just pulls out)