How do I download one tune onto a memory stick?

[threelittlebabies]

Yes I know it's a stupid question, and sorry for being a technophobe!

Am doing a powerpoint presentation tomorrow and wanted to add an appropriate son to the end slide. Which is the best site to use and how do I save it to the memory stick? (or is that self-explanatory thus making me feel even thicker than I did!)

Thanks in advance

wee bump, 'cos I really do need to know and really am that stupid!