Ritesh,
You cannot single LED in parallel.
Each LED will require about 1.6 volt and depending on the LED, will handle up to around 20 mAmp. You need to get the data sheet for the types you are using.
Assuming each LED is 1.6 volt, you can connect 6 LED's in series and connect them directly to your 9 volt supply. In this configuration, the LED current will be around the same value as the current rating for each LED. If the current is too high, then connect 7 LED's in series. You need to test this with a meter.
The transistor BC337 is rated at a collector current of 500 mAmp at a junction temperature of 150 degree C.
The base current has to be 50 milliamp for this collector current. At 50 mA, the base emitter voltage is 1.2 max. The base drive resistor will be 150 ohm for your 9 volt supply.
this base resistor will allow the collector to carry 500 mA. The maximum collector emitter voltage is then 0.7 volt.
If each group of 6/7 LED's carries 20 mAmp, the you can connect 25 sets of LEDS in parallel on your 9 volt supply.
Each group of LEDS in this arrangement will have different levels of brightness due to differences in the forward voltage of each LED. If you want to improve this, you need to stabilise the current in each group of LED's by arranging say only 4 LED's in each group, and using a series resistor to give say 20 mA in each group of LED's. That would need a resistor of say 130 ohm for each group of 4 LED using 20 mA led's.
hope this helps.