To understand the basics of LFO, you have to understand what type of machine you are using for production and most importantly, what kind of music you are producing. Every machine is made up of different Oscillators. (circuits used to create audio signal). LFO's are Low Frequency Oscillators. (think Moog, Roland Jupiter, Dave Smith Prophet '08 etc...) these instruments are famous for having some of the best LFO's in their synth engines.
LFO's can be implemented in modulating a sound. You have Phase, Stereo Panning, Filters, Amplitude, Vibrato and Tremelo just to name a few examples of how you can route your LFO's.
You can start by doing some research on these instruments and other synth instruments on-line. You will find synth keyboards or sound modules to have more of a varitety of LFO's. Some sample-based drum machines don't offer as much. I know the MPC4000 has many to offer in it's efx menu. But you need the efx card installed for that.
Listen to EDM music. You will find alot of LFO's being used in their music.
Check out the links clint242clint posted as well.
-DJ AL Rayder