i just bought my new blackberry 8900 and i don't know how long do i need to charge it so anybody knows something please tell me

Usually a couple of hours on the initial charge does the trick. The battery indicator will tell you when it is fully charged.

You charge it until the blinking orange/yellow light turns to solid green. The length depends on how much charge the battery had when you started charging. If the battery charge was 60% when started charging, that will take less time than when the battery had 20% charge initially.

But note, the LED will not blink orange/yellow and turn green if you are charging while the device is ON.
This only happens when the device is OFF

In such cases, one might use
Options --> Status
to see the battery level. Battery level = 100% if fully charged, and less if not fully charged. Then, the user can decide accordingly.

true.
I was merely noting that above because as a new user they may expect to see the LED flash when they are charging while ON.

ok thanks