try to add class col-md-offset-2. So you have “2-col space” before your columns.

So final code is:

<div class="row">

     <div class="col-md-offset-2 col-md-4">aaaa</div>
     <div class="col-md-4">bbbb</div>

</div>

I have 2 col-md-4 divs in one row div like so:

<div class="row">

     <div class="col-md-4">aaaa</div>
     <div class="col-md-4">bbbb</div>

</div>

My question is how do I center the col-md-4 div. I have 2 more rows above this that have 3 col-md-4 divs and this 3rd row creates and empty space because I have 2 and not 3. I hope what I am asking makes sense.