Introduction
Setting up a connection between your computer or phone (master) and Arduino project (slave) using Classic Bluetooth is fairly easy and straight forward. The complication is the power supply and voltage for the serial port connection. The communication port with the Bluetooth device requires 3.3 v. To reduce 5.0 v to 3.3 v you need a voltage divider.
Online manuals
There are many manuals and tutorials for how to wire and sketch your Arduino Bluetooth connection. To get an updated manual you should probably consult a search engine. The How to connect an Arduino Uno to an Android phone via Bluetooth by 42 Bots Hobby Robotics and Electronics Blog, contains a good summary on the power and voltage issue. Also How To Meachatronics have an OK Arduino and HC-05 Bluetooth Module Tutorial.
Voltage divider
Resistor Color Code Calculator
Wiring
