Battery question

I just recieved my first RC heli , a Walkera Dragonfly 5.o
It came with a Lithium Poly 7.4v 720mAh battery and wall charger.
I thought I read something about these types of batteries blowing up if over charged . The heli manual doesnt say anything about the battery , ie. how long to charge.
The wall charger has a green and red LED .
Does anyone know how long this battery needs to charge ?
AND can I just plug it in and go to work or let it charge overnight while I sleep ?

Thanks. joe

I have a charger that come with the e-sky honeybee, i dont know if it's the same...

red flash = no battery
red & green light = charging
red light = complete
red & green flash = Charge error

dj cutter