An TSOP1738 is an 38Khz infrared receiver with integrated demodulator, Nothing more.
You must know the timing and coding of the modulation signal to decode it and show it onto your display.
To get the rising and falling edges of the Output signal of the TSOP, You can use an external interrupt e.g. INT0.
To get both in one Interrupt routine you can switch the interupt sensing in the accoring interrupt.
E.g. Interrupt sensing is switched to rising edge. The rising edge of the signal appears.
The interupt will be executed, at the end of the interupt routine you switch the interupt sensing to falling edge.
To get the len of the high or low period, You can read out a free running timer ( Timer1 ) in the INT0 interrupt routine. The time between the rising edge interrupt result and the falling edge interrupt result give you the high time of the signal, for low time the opposite.
You also can use the input capture interrupt instead the INTx. The actual count of TCNT1 Register will be stored in the ICP1 Register when interupt appears. The sensing ( rising, falling ) can switched as same as the INT0.
When the whole sequence is into your controller you can compute it and put it out on your display. You must know the time between 2 sequences to use it for restarting the code sampling.
Sorry, I've no code exeample, but i've used this method to measure servo pulses ( model building ).