You can specify multiple column sizes in Bootstrap. The following HTML should get you going
<div id="dashboadMainId" class="container">
<div class="row">
<div class="col-lg-1 visible-lg fixed">Left</div>
<div class="col-md-6 col-lg-5">TEST</div>
<div class="col-md-6 col-lg-5">TEST</div>
<div class="col-lg-1 visible-lg fixed">Right</div>
</div>
</div>
In that example, we're using the responsive utilities (http://getbootstrap.com/css/#responsive-utilities) to only make the left and right columns visible on large screens and the grid options (http://getbootstrap.com/css/#grid-options) to make the central columns 6 wide on medium sized screens and 5 wide on large screens. The left and right columns are 1 wide on large screens.
To make the left and right boxes stay static, you will need to apply position: fixed
to them using CSS:
.fixed {
position: fixed;
}
You may need more styling than that depending on what you're trying to achieve though, but that's essentially how you make something static on a page.