SEO is a skill you wont get right first time...
Go to Google Web-Master Central and Register for there helper tools and analytics, these can help.
As said, go to the search engines websites, all have free submissions, they might not advertise this, but most do. Once you are in one, then others tend to follow in anycase.
Google, MSN, Yahoo are the main places you want to focus.
The make the page as best as possible, you need to add (Meta Tags) (Meta Title) (Meta Description). To get the best results, each any every page should have these three attributes in a unique sense, so dont just copy and paste the same data, make it relevent to the page.
In each of the three, dont repeat the same word more than three times. If you put, Camera, Digital Camera, Film Camera, DSLR Cameta, Etc Camera this would have Camera Five Times, so watch it.
Make sure that each Meta Tag Keyword is in the page and is visable. Times of hiding text, or making it blend into the background have gone. If you do this, Google know, and that will hit your placement.
Make sure you use <H1> AND <H2> tags. The main keyword of the page should be in this title/heading. Each page should have one or at the most two words to sum it up. Images have <alt> tags, get the keyword in there too.
There are a million and one other things you can do, each thing helping a very little, but the sum of them help heaps. The more pages and the more optimised a page is, the better. Type in Google a keyword and then see who comes up tops and check what they have used in their tag lines.
EBay are masters at SEO. Every page has different Keywords, Descriptions, titles, headings and text, each page is unique, and thats why they are more or less on each search.
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Here is some sample HTML code to demonstrate the key items to a good page layout.
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<head>
<title>Untitled Document</title>
<meta name="keywords" content="KEYWORDS GO HERE" />
<meta name="description" content="DESCRIPTION GOES HERE" />
</head>
<body>
<h1>TITLE ONE GOES HERE</h1>
<h2>TITLE TWO GOES HERE </h2>
<p>PUT SOME RELEVENT TEXT HERE THAT INCLUDE ALL THE KEYWORDS</p>
</body>
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I use a web forum called
www.jimworld.com (http://www.jimworld.com)
Ask as much and what you like here, its all about SEO, there are many masters there, its all free, and read all the other articles, and just keep track of your progress, you can use Google Web-Master Central to do that.