I have tried for many hours to get 2 DC motors running with an arduino, however, I cant for the life of me solve a few problems. Firstly, I want to have the motors both running at 4.5V, howverthe arduino can only supply 5 it seems. Secondly, I am trying to control them using an H-Bridge, not a motor shield, as I cannot afford one at the moment. Any guidance on both powering and controlling these motors would be greatly appreciated.
You should never power motors from the Arduino.
It can't provide enough power, and electrical noise from the motors will damage or reset the Arduino. Always use a separate motor power supply and connect all the grounds together.
For more information, describe the motors (voltage, running current and stall current ratings) or post a link to the data sheet or product page.