How Search Engine will know about newly created website or webpages? Generally they keep index of all the website their bots visit but again what if you created your website today? It can take many weeks or may be 1-2months before Search Engines like Google can visit your website and then index it.
So, if you want to speedup this process then you can submit your website in Google, Bing, Yahoo and other search engines and then they will quickly visit your website and index the content of the website.
Make sure you have followed all the basic On Page Optimization Techniques before you submit your website in search engine. Because it is wise to go to war with full preparation then just go to war and then start the preparation.