How to set up layouts?

[winston2020]

Hey all, first time poster here
Well, I've been doing web stuff as a hobby for several years, but I never focused on browser compatibility, or server-side security measures. So my new project is to build a simple blog site as "correctly" as I can.
To that end, I've designed a blog post which uses tables extensively, and I was wondering if there is a cleaner solution, perhaps using css?
Unfortunately, my site is localhost only at the moment, but I can post the code below.

<table width="650" border="0" cellspacing="0" cellpadding="0" align="center">
          <tr>

            <td width="29"><img src="http://localhost/images/tl.jpe" /></td>
            <td height="29" background="http://localhost/images/top.jpe"><!-- TOP, EMPTY DATA--></td>
            <td width="29"><img src="http://localhost/images/tr.jpe" /></td>
          </tr>
          <tr>
            <td width="29" background="http://localhost/images/left.jpe"><!-- LEFT SIDE, EMPTY DATA --></td>
            <td valign="top">
            <!-- USER POST TABLE -->
            <table cellpadding="0" cellspacing="0" width="100%" border="0">

            <tr>
            	<td width="80" valign="top">  <!-- AVATAR DATA -->
              	<img src="images/winston2020.jpg" width="60" height="60" border="2" />
              <!-- END AVATAR DATA -->

              
            	</td>
            	<td>
				<table width="100%" border="0" cellspacing="0" cellpadding="0">
                  <tr>

                  		<td>
                    	<!-- BLOG TABLE -->
                        <table width="100%" border="0" cellspacing="0" cellpadding="0">
                          <tr>
                            <td>
                            <!-- BLOG POST TITLE --><strong><div id="title_87">Hello!</div></strong>                           
                            <!-- END BLOG POST TITLE -->
                            </td>
                            <td align="right" width="85">

                            <!-- EDIT COMMANDS -->    
                            <!-- END EDIT COMMANDS -->
                            </td>
                          </tr>
                          <tr>
                          	<td colspan="2">
                          	<!-- AUTHOR AND DATE --><em><font size="2">Wednesday, November 17, 2010 | 01:36 AM | by winston2020</font></em>                          	
                          	<!-- END AUTHOR AND DATE -->
                          	</td>

                          </tr>
                          <tr>
                            <td colspan="2">
                            <!-- BLOG POST DATA --><br/><div id="content_87">Why, hello!</div>                            
                            <!-- END BLOG POST DATA -->
                            </td>                            
                          </tr>
                        </table>
                        <!-- END BLOG TABLE -->

                    </td>                   
                  </tr>
                </table>
                </td>
                <td width="80" valign="top" align="left">
                </td>
                </tr>
                </table>
            <!-- END USER POST TABLE-->

            </td>
            <td width="29" background="http://localhost/images/right.jpe"><!-- RIGHT SIDE, EMPTY DATA --></td>
          </tr>
          <tr>
            <td width="29"><img src="http://localhost/images/bl.jpe" /></td>
            <td background="http://localhost/images/bottom.jpe"><!-- BOTTOM, EMPTY DATA --></td>
            <td width="29"><img src="http://localhost/images/br.jpe" /></td>
          </tr>
        </table>

[Frederick Lave]

Hi, I am setting up my new sub domain site and need help since I am new at this. Okay, so I have my layout set to go.
- How do I install it?
- Do I upload a file for it or something or paste it in a folder?
- How do I make it so that the layout shows up on all pages?
- If I set up one page, and look at a new page, will all the stuff on my site show up, or just that one page in particular?

about the last question: I made the home page, then made an about the website page. when I went to look at my webpage, I saw that stuff on the home site (links in the navbar) didn't show up on the about page.

also, what do these mean - .html, .php, .index, .text

thanks so much for those who help!
please don't just give me a site with 1321354 tutorials to go read, unless it is really, really helpful.