I'm always leary of automated root tools because you don't always know if it contains any malware. Not to mention the method of rooting is very device specific. It's not as simple as knowing your OS version. You need to know the device make and model, the software build version, and carrier version (if applicable).
For example a rooting method for a Sprint phone isn't likely to work on a Verizon version of that same phone. Sprint could also release an update that closes the backdoor that was used to root that phone and a new method must be found.
If you let us know your specific device, someone here may be able to help you more (I haven't rooted in years), but otherwise I'd suggest looking at a place like the XDA developers site for specific rooting instructions. That is, assuming a method has been found for your device in the first place. Popular devices get the most research for rooting, and cheap no name devices are unlikely to be researched. It'll require some legwork on your part to make sure you understand the process before you attempt it.