emitter follower conofiguration
The simplest solution is to put the IR transmitter in the colelctor and have a small valued resistor in the emitter. Thus, if you drive the base with 3.3 volts, the emitter voltage will be at about 2.6 volts and this will appear across the emitter resistor. If the emitter resistor is 26 ohms then the current that flows is 100mA - this current (maybe 99%) flows through the collector and IR transmitter. There are more accurate and higher power versions of this but get the basic circuit working first.