Repositioning the existing div tag at the position where div tag already exists

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Javascript

CSS

HTML

jQuery

I am new to web development and have tried all the code help that i could get from internet.
I have a series of div tags placed in a single div tag
like

<div class="Draggable" id="MainDiv">
<div id="firstdiv">...</div>
<div id="seconddiv">...</div>
<div id="thirddiv">...</div>
</div>

The div tags are generated at runtime so the id's are random.the id given above are just for making the readers understand my problem.
The actual task that is to be performed is to reposition firstdiv between seconddiv and thirddiv and so on by dragging the respective div at runtime.

Thank You in advance..