Step 1 - Connect your arduino to computer
Connect your Arduino Uno board with the USB cable to the computer . No any circuit connection , only Arduno Uno itself .
Step 2 - Open and Upload ArduinoISP sketch
By default Arduino IDE comes with an ArduinoISP sketch . All you need to do is to open it up in your Arduino IDE , open ArduinoISP sketch , then upload the sketch to your Arduino .
Now your Arduino Uno will become a main programmer / burner .
Step 3 - Connect the circuitThe below diagram shows how to connect ATMega328p after you have done uploading you ArduinoISP sketch .
Step 4 - Burn bootloader to the Atmega328p
The next step is to burn the bootloader .You can burn the bootloader , by selecting Tools -> Burn Bootloader . Make sure you have chosen the correct board type before you do that.
Now , everything is ready, and all you need to do is to write your sketch and then upload it. The ISP sketch that your burned into your Arduino , will take care of the rest .
. . . . . Next - Arduino Standalone - Test your Atmega328p