How the batteries should be cherged is ususally printed on them, if it deviates from the general rule.
The general rule is charging them at 1C. 1C means that you should charge the battery with a current answering to the batterys specified capacity in mAH, divided by mH (1000).


Practicalltly, it means that a 1000 mAH battery should be charged at 1 A, a 3300mAH battery at 3.3 A, etc.
That is a charge rate of 1C. Some batteries can be charged faster, and this will be specified on the battery. If its for example 5C, then you just multiply the 1C Charge figure with 5.
Wich means, 5A for the 1000mAH battery, at 5C.