Make your own Arduino Uno board for experiments:

Components List:
  
1. Atmega328 Kit (Atmega chip with boot loader)
2. USB to Serial Adapter
3. Piece of Vero board
4. 2 x 20pf ceramic capacitors
5. 1 x 10K Resistor
6. 1 x 1K resistor
7. 1 x 0.1nF capacitor
8. 1 x LED
Our Atmega328 Kit comes with bootloader preloaded.
Atmega328P chip has 32kB Program Memory(flash) , 2kB Ram and 1kB ROM

What is a boot loader:
Bootloader is a small piece of code that resides in the high end of the program memory space. Once the reset button is pressed (hardware reset), Micro Controller starts executing the code from Boot loader start point. This code waits for few seconds reading the serial input (during this time LED connected to Pin-13 flashes 3 times). If there is any thing coming through serial port, it loads that code into the Application code area and start executing that code. 
If there is nothing coming in during this few seconds, it just start executing from Application start point. Whenever you reset, the LED flashes 3 -times before executing your Arduino code.

Solder the components on the vero board as in the schematic, connect to the USB Serial adapter.
Board gets the 5V power from USB through the adapter.
If everything works, test it by pressing the reset button,  The LED connected to pin-13 should blink 3 times.

Now it is time to start programing with Arduino IDE.
Download latest Arduino IDE here. Install it on the PC (or MAC), run it.
You also needs to download and install the USB driver software for CH340 USB/Serial chip here.