It is not so easy to tell you with a few words do this and that and is over. Any template has it's philosophy in styling and you must be experienced to change it and make it look, as you like.
The main files of the template on which you have to work are layout.css and index.php and of course later you will have to work and on customize.css. This you have to do is to change width in divs from pixels to % and to work with float element. Font size (px or em) is not so important. The template also has a trick with column which is called rightcolumn but works as left. The same job you have to do also and on files layout-rtl.css and customize-rtl.css for Persian language.
You have to know also that using such templates, you can not make some modules which are made and working with specific dimensions in pixels to "sit" on various module positions, as you like. So even if you make it, you may face problems later with this.
Ks-net who is the creator of the template could tell you more. But if you are not familiar with html, css and php it will not be easy to do it by yourself.
There is also the solution to order here
a custom one template as you like it.