element placement question

[liunx]

I wanted to know if it is normal when aligning images on a page with css to be constantly fliping between the browser and the code to check for placement. For example, I wanted to put a logo.jpg in the top center of my family homepage, I would set the left margin to x amount of px and it would be off. So, I would go back make and adjusment and check again on the browser. Is there an easeir way of doing this?? And how does css setup the margins, from the left border of the jpg, the center of the jpg, or what? You can check out my site in question at <!-- w --><a class="postlink" href="http://www.mjmcdonaldfam.com">www.mjmcdonaldfam.com</a><!-- w -->. Any help would be appreciated. Thanks.Accidently sent this thread twice, my bad.