User Guide for AT89C51RB2_3V3_EVAL           
AT89C51RB2 basically shares all source code with AT89S52-gLCD-STK1(link)
The only difference between these development boards are
1. AMS1117 linear regulator in AT89C51RB2_3V3_EVAL outputs 3.3V
2. Sipex 3232 for U2 because of a lower Vcc
3. Monochrome display in AT89S52-gLCD-STK1 whereas 65k color display module
    in AT89C51RB2_3V3_EVAL
4. FLIP software for ISP programming can be employed eliminating the need for
    an external programmer. The only action you need for ISP are
              (a) connect a straight RS232 cable to PC's COM1
              (b) shut PSEN pin to ground at the expansion port
              (c) press RESET button to run the bootloader program from ROM
              (d) launch FLIP, browse to the *.hex file you want and press program
Thus, refer to Users' Guide of AT89S52-gLCD-STK1 as a reference.
Simply replace the header REGX52.h with REG51RB2.h and select the correct device from Target Options. Several examples have been included as illustration.