How to create the Text-box responsive

You should almost never use inline style sheets. As for your code, your div with the class row should be inside the div with class container-fluid. Inside that should be a div with the column class and then in that should be the paragraph.

Your CSS should be in an external style sheet something like this.

.my-text{
  height:500px;
  width:700px;
  border:1px solid #ccc;
  font:16px/26px Georgia, Garamond, Serif;
  overflow:auto;
  position: relative;
  left:350px;
  top:16px;
  background-color:white;
}

However, as Chris had stated, you shouldn't be specifying a width as that goes against the fluidity of responsive design.

.my-text{
  position:relative; /* probably don't need this */
  left:350px;        /* probably don't need this */
  top:16px;          /* probably don't need this */
  height:500px;      /* probably don't need this */
  font:16px/26px Georgia, Garamond, Serif;
  background-color: white;
  border:1px solid #ccc;
  overflow:auto;
}

Your HTML should look more like this.

<div class="container-fluid bounceIn animated">
    <div class="row">
        <div class="col-md-12 my-text">
            < p>My long text in here…< /p>
        </div>
    </div>
</div>

If you need more help then this then, like Jo and Chris have stated, you need to have a better understanding of CSS and HTML.

Saj