Each search engine works a little differently but most have general characteristics in common. Unlike a directory, which you have to manually submit to and rely on a listing made by a human editor to determine your ranking, a search engine uses your entire page, sometimes your entire site, to determine a ranking. Also unlike a directory you don't need to submit to a search engine to be included in them, although submitting may expedite the process, because search engines send out robots (also known as spiders) that crawl the Internet following links from one site to another. So the only thing you actually need to be listed in search engines is a link to your site from a site already in the engines.
Each search engine will have a different way to submit. With some it's a simple form, with others you have to pay to submit. Regardless of the submission process you only need to submit your root URL to each engine (assuming that internal links can lead a robot to all your pages). You also do not need to resubmit any time in the future, there is no need to repeatedly submit your site in order to maintain your ranking. Search engines periodically revisit every site in their index so your listing will stay up to date anyways, and resubmitting won't get your listing updated any sooner.
Once you've submitted you should watch your site statistic logs, you should notice spiders visiting shortly, how long it takes could be a few days to a month or more depending on where the search engine is in it's update cycle. To identify the spiders you will need to look at their HTTP_USER_AGENT, also known as their web browser. For a full listing of robot user agents see our article "Search Engine Robots."
Once you notice the spider in your logs it can take additional time for you to actually be listed on the search engines. Not all engines update their listings as soon as new ones are available, some will wait up to a month or more before publishing the new listings so that they can update all sites at once.
Getting into search engines can often be as timely a process as getting into directories, even though search engines use robots that automate the process. You should be patient and refrain from resubmitting your site. The only time you should resubmit your site is if you notice a search engine spider in your logs but 6 weeks go by without your site appearing in their index, or if your site gets dropped from the index. At the same time don't worry about over submitting, search engines generally don't mind that anymore.
Search engine optimization is the practice of tweaking a page so that it is ranked well under target keywords in the organic, or natural, search results (organic results mean not paid placement). It differs from search engine marketing, which is the practice of tweaking Pay-Per-Click campaigns for optimum ROI (return on investment).
In the earliest days of the practice all a webmaster had to do was repeat a keyword on their page over and over again and the page would rank well for that keyword. This was of course easily abused and search engines had very poor relevancy. Then Sergey Brin and Lawrence Page founded Google based off an algorithm that used both on-page and off page factors and the search engine world changed forever. Now every major search engine uses off-page factors that Brin & Page pioneered, so while they are all different, when you're focusing on the fundamentals the changes you make will be beneficial for all search engines.