Your First query :I personaly think its not really good to use <body> to put your bg in it :/ why ? because its always better to use a style.css instead ! youll see once you coded your site style.css will be cool.
So create a new .css document... well go to notepade and than save as .css mostlikely
style.cssonce done put this into it :
CODE
body {
background:#FFFFFF url(images/backgroundimage.gif) repeat;
}
(modify the image name and filetype)
ofcourse other atributes can be added... such as color, paddings.. margin..
Once saved

put this style.css next to your HTML pages

and inside ALL your html pages between the <head> </head> tag add this line of code :
CODE
<link rel="stylesheet" href="style.css" type="text/css" />
Your second query :this is a link code :
CODE
<a href="http://www.google.com">Google Web Site</a>
so when you clic on this "Google Web Site it sends you to google.com. Simple ?
well you can than if you want add a target...
so lets say you want to have a link to open in a new window you just add the
target="_blank" so :
CODE
<a href="http://www.google.com" target="_blank">Google Web Site</a>
you can put a iframe as a target.. as
target="blabla" so lets say you had a :
CODE
<iframe name="blabla" width="400" height="400"></iframe>
inside a corner of your website... well once you clic on Google Web Site it will traget your google page inside the 400x400 iframe on the corner of your site

you can add many things with a href

HOPE IT HELPS