These are microcontrollers.

Just about everything to run the processor are built into the processor.

Your breadboard must supply a stable voltage (i.e. low resistance in the power supply lines and decoupling capacitors around the chips).

And it must supply a clock source - the datasheet for the processor will show how to connect a crystal to the processor.

And it must supply an ordered reset. Possibly a capacitor + resistor. Even better with a specific chip designed for the task.

That is enough to get your processor up and running.

If you want to send commands from the PC, you may need a MAX232 with capacitors (lots of schematics around how to do it) to interface the voltages of the microprocessor with the RS232 levels used by the PC serial port. Or you may buy a USB serial port that uses 3.3V or 5V logic levels on the side connected to your processor and on the PC side looks like a standard USB-connected serial port.

For your motors, you will have to decide how to drive them. You may design this using discrete power transistors or buy special driver chips. The datasheets for the driver chips will show how to interface them.

So in the end, you can break your problem into many small problems. And every little problem can be solved by reading the application notes and datasheet for your processor and by googling around for other 8051 processor designs used to control things.

The whole point with a development board is that it is just a generic platform for you to play around with - but these generic circuits will show up in hundreds and thousands if you google around. Have you looked at the helpful links on this site? Check out the menu choices to the left of the page.

And if you really do want a schematic of your specific board, you will normally get one when you buy the board. And the manufacturer often have links to the schematics on their web site. Have you tried to contact the manufacturer or the company you got your board from?