The backlight on my speedo went out the other day, now I cant see how fast I'm going at night. It's probably just the bulb but I dont know. How do I fix this?

shine a flashlight on it  :lol:
....or take off the two nuts on the back ogf the speedo that is holding it to the mounting plate. depending on the slack you have you may need to disconnect the speedo cable from the back of it, no biggie. pull out the speedo, you will see the bulb socket plugged into the back near the top. pull it out replace with a 194 bulb and there you have it. takes about 10 min. have fun.  

DO they make red bulbs in that size?

i believe so. i got blue ones for mine. you should be able to get them at any parts store.