The GMER site includes sample logs of some common threats. You can compare results against the samples to see if any of the entries in your log match up. If you're unsure, or just don't know how to interpret the log data, you can also email a copy of the log to the GMER developers and they will help with analysis.
GMER is not the only option. You can also look at other specialized rootkit tools like Kaspersky's TDSSKiller. For more information, check out the GMER FAQ. You can also send an email to firstname.lastname@example.org with any questions about the software or how to use it.