This site: http://www.hebeiltd.com.cn/?p=zz.led...tor.calculator has a resistor calculator for LEDs in series or parallel. You need a DC power source (batteries or power supply), a resistor of the correct value, your LEDs, and a switch if you want to turn the LED off. As to the specific form the light takes, that's entirely up to the builder.
Finding, buying, and shipping parts can get expensive if you source all the parts to build yourself. There are LED flashlight bulbs available in red (and perhaps yellow) or little portable battery powered arrays as seen here: http://superbrightleds.com/flashlights.htm that might be cheaper and just as useful as home-built. You could just slip a red LED into a flashlight and bounce it off the ceiling, or grab it an point it where you need it at the moment.