Calculate resistor value of Optocoupler & Transistor
The following should give you a good start:

$$ R_1 = \frac{3V - V_{FW,input} - V_{FW, LED}}{I_{FW}} $$

and

$$ R_2 = \frac{5V - V_{CE,output} - V_{BE, 2N5551}}{I_{FW} \cdot CTR} $$

Inserting some values (from the datasheets):

$$ R_1 = \frac{3V - 1.4V - 1.2V}{5mA} = 80 \Omega \approx 82 \Omega $$

$$ R_2 = \frac{5V - 0.2V - 1V}{5mA \cdot 0.5} = 1520 \Omega \approx 1.6k\Omega $$ 

I have to warn you that you have two LEDs in series and the supply voltage is relatively low to supply them. I considered a voltage drop of 1.2V across the second LED which might be actually higher.