Simple 8051 internal ADC code

I have been trying to get the 8051 ADC to work but the examples I found where not very clear. I can understand the modifying of the SFR's but when giving the output to an LCD data function, I only get either 255 (full scale 8bit) or 000.

If anyone can supply me with a simple ADC program with some explanation how to get the value I would really appreciate it. Thanks