Taking photos of screen

Hi i would like to know if anybody can tell me how to make the photo you take of your desktop smaller i'm new to macs and pc's for that matter so i dont know **** about anything my friend who's a windows lover say's macs r ****e and you cant do anything with them (he's super good with windows and hack's into my college networks and everything) anyway he wants to see what my desktop looks like and i dont know how to turn the photo i take of my desktop into a jpeg image.

Thanks any advice would be good

when you open up the file in preview go to file export and export it as a jpeg

I would just take a snapshot of the desktop and email that.

yeah. command+shift+3 will take a screen shot and put it on your desktop

These a program called freesnap which do all that to, but will save it as a jpeg, or what ever format you want.