In order to determine how fast to charge the battery, you need to know it's capacity (in milliamps or amps), and also it maximum charge rate in "C". The 30C you listed is most likely it's discharge rate, since as far as I know, no batteries can be charged at 30C.

Essentially, you multiply the charge C rate by the capacity of the battery.

Example: Let's say I have a 1500 mah battery that can be charged at 2C. That means I can charge it at 1.5 amps (i.e. 1500 mah) x 2C = 3 amps.

I hope my explanation is correct. Anyone who is more knowledgeable, please feel free to correct anything.