How to use acquia_marina theme for adding user-defined blocks on front page

Hi All
I have two questions,please look at as follows:
1. I am using acquia_marina theme,Now,I want to add user-defined(noted:user-defined) blocks on front page ，for example,Add four blocks on front page,every block put some comments or pictures!
2. I had made one region by adding its name in INFO file and adding some code in page.tpl.php,Its name is "missionp" ,Now I want to put it on Primary menu,But I cann't set their space,their space is quite big now,I want to reduce their space! it is my setting in some files as follows:

CSS file for missionp:
div#missionp
{ margin:0;padding:0; width:300px;}

CSS file for Primary:

#primary-menu { /* menu layout */
display: block;
float: left;
font-family: Myriad Pro, Myriad Web Pro Regular, Lucida Grande, Geneva, Trebuchet MS, sans-serif;
font-size: 1em;
font-weight: bold;
margin:0;
padding: 0;
position: relativet;
text-transform: Capitalize;
}

please master-hand tell me how to do as above,thanks a lot!