The easiest way to update the drivers for your graphics card is to obtain the latest drivers from the AMD website. Please use the linked word and navigate to the support form from where you can download latest drivers.
For your card the path should be Desktop Graphics > Radeon HD Series > Radeon HD 4xxx Series PCie and then select the operating system that it's installed in your computer. If you want a fast way, I suggest you just download the driver pack and run it. You only need to follow the on-screen instructions and your card will be updated.
Please note that a restart may be required for the whole process to complete successfully.