Datasheet Very Clearly Describe. Freely available.
Don't understand your question, really.
VDD = Voltage to Digital Circuit (Positive 5V power supply)
VSS = Ground
For starting out with Microcontroller, start with the Right processor that can sustain you with many projects and active community discussions in the market.
I recommend you to start with Atmel AVR [now bought over by microchip], chiefly the Arduino/GCC compilers and Atmel studio are freely available and kits are cheaply abundances and fast controller.
for 14 pins for example, you can start with ATtiny84. Pinout will not be the same.