Putting a  tag around fields in nodes
To provide the custom markup, you have to override the tpl.php file for that node.
To override this, follow these steps :

1) Copy the node.tpl.php in your theme.

2)Rename it node--"yourContentTypeMachineName".tpl.php
for example my custom file is now node--image_archive.tpl.php

3) to test it out write some text(anything) in your new node.tpl file.

4)paste your new node.tpl file back in you theme folder

5)Clear all cache

Now access all the field and provide the custom markup as you want.