Iadj should be in the datasheet for the device. It's a fixed amount which is very small.
The output voltage is determined by R1 and R2.
The line from the output through R1 and R2 to ground, forms a voltage divider circuit which is
measured by the bottom connection on the chip, to regulate the output voltage.
The Iadj in the equation, is an adjustment to the voltage divider equation, to compensate for
the small current going into the voltage sensing connection of the regulator chip.
I am not sure what Cadj is for at all.
If you are trying to make 4.3V, make sure you read about how much Vin has to be, compared to Vout.
It has to be 0.7V or 1 volt more than Vout, that will also be in the datasheet. You might not be able
to get 4.3V from a 5V supply.