go to this site then option will appeare like this so follow the steps which i have given there.:)
Step 1: Select the type of system that you have:
select there desktop graphics.
Step 2: Select the product family your product belongs to:
select there radeon hd series.
Step 3: Select your product:
select there radeon hd 6xxx series pcie
Step 4: Select the supported operating system that you have:
which ever operating system you have choose it in the option.
step 5: display results
click on it.
and after that download driver.