Hi Yasir,
Can you provide a screenshot of your actual dashboard so we can provide further guidance? Normally it is quite straightforward to centre a dashboard by placing it into a container like a panel or grid and then applying one of the following techniques:
1) Set left and right margins to equal fixed values and the width to auto for flexible width centring or;
2) Set left and right margins to auto and the width to a fixed value for fixed width centring.
Regards,
Mustafa.