No one has created a temperature monitor that will accurately guage the temperature of the FX processors under about 26c. Once you pass that threshhold, readouts from say, Coretemp should be fairly accurate.
As for overclocking: http://www.youtube.com/watch?v=MckeAmnDeTk
This is a good jumping off point. You should do more research on overclocking. Google overclocking for beginners and read some articles. Also, google for 8350 overclock settings. Find some people with a similar setup and see what numbers (multiplier, voltage etc) they have had luck with. You can start below their numbers and work your way up from there. Dont get discouraged if the numbers they use dont work for you. Overclocking is tricky. Someone could have the exact same setup as you, but different settings for an overclock. Getting it stable is the most important thing, and that comes with hours of testing.
Make sure you pay close attention to temperatures on the cpu AND the motherboard when overclocking. Your CPU might not break under the pressure, but thats not the only thing that gets hot. I like using a thermal gun to spot check areas on my mobo while I'm overclocking.
You will want to make sure you dont have a problem board. Check this list: