Meta tags r tags that provide info about the page. One of them is the keywords tag. Meta tags r placed inside the <head>. Like:

<head>
<title>Untitled Document</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<meta name="keywords" content="one, two, three, four">
</head>

U can register manually by going to each search engine separatelly. There u can find instructions on how to register.
U can wait a couple of months (or more) for the sniffer robots to pass from your page.
U can use a submission program to do the work for u (this costs cause u must buy the program).