Search Engines work automatically with "robots" called spiders which read and index your website. In order for them to find your website, you must let them know you exist. This is done by inserting <META tags> in the background of your website and submitting your website for their review.
Your website should have <META tags> defining the keywords people would use to locate your website; <META tags> with a description of your site so that when they do find you your site is described correctly.
Website directories, on the other hand, are reviewed by humans and each directory has different requirements.
But what they both have in common is that they all have particular rules to avoid spam. You must have some keywords in your page title but not too many; the title can't be too long; the descriptions should contain as many keywords as possible; and so on.
This work is very complex and intricate. but the good news is that it only has to be done once for each page.
I offer a personalized search engine submission work and then submit your website to over 100 search engines and directories. This means that I spend time making sure that each page gets the optimal placement on search engines.