This will create 2 columns centered in the 12 column grid system

This approach uses Bootstrap's own offset classes so it requires no change in markup and no extra CSS. The key is to set an offset equal to half of the remaining size of the row. So for example, a column of size 2 would be centered by adding an offset of 5, that's (12-2)/2.

<div class="row">
    <div class="col-md-2 col-md-offset-5"></div>
</div>