Modding LEDs off a battery

I am working on a model for my architecture class and i was wondering if someone could give me a walk through on how to run a few LEDs off a battery, nothing bigger then a 9 volt.

thanks

 

I need to do this aswell for a point of sale i'm making in my product design class, like mrobitz it can be no bigger than 9v and i need to run about 7+ leds.

 

take leds rated for what the voltage on the battery is and hook up em. + leg of led to + off battery, same with negative. if you have a few led make them like this:
(BATTERY +)--(+)--LED--(-)----(+)--LED--(-)----(+)--LED--(-)----(+)--LED--(-)--(BATTERY -)

just connect them in a big series. - to +. thats it.

 

+~~~~~(+)~~~~(+)~~~~(+)~~~~(+)~~~~(+)~~~~
-~~~~~(-)~~~~(-)~~~~(-)~~~~(-)~~~~(-)~~~~

If you can understand my diagram wire them like that you can run say 25+ leds off a 9 volt batt but they may only last 10 mins

 

http://lsdiodes.com/tutorial/

there you go all you need

 

Jesse you are awesome, finally something for the complete noob..!

 

http://metku.net/index.html?sect=view&n=1&path=mods/ledcalc/index_eng

on that LED calc what does voltage dropped mean?