is there any sites in the web that has a beginner's tutorial on c8051f320 mcu programming?
You're unlikely to find a tutorial aimed at that specific model of 8051 microcontroller, but there are plenty of tutorials out there on the 8051 architecture in general, as well as microcontroller programming in general. Specific applications always require knowing the surrounding circuitry and reading the data sheet.
This is one of the best online resources for all things 8051 which includes the 8052, 8031, and 8032. It has a tutorial on their website that gives you a feel for the 8051. That can give you a good head start.
Hopefully, you do have a schematic for your board. You'll need this to determine which I/O pins to wiggle as well figure out the address range of each device.
Make sure you have the trusty data sheet for the MCU as well as data sheets for all the devices connected to the MCU