Well first you need a demand for whatever your website may be geared towards. Second, you need content. Without content to market, your marketing campaign will flop. Third, you need to know who your target audience is that you will be feeding the content too. Fourth, you must focus on SEO. Getting at the top of search engine rankings is key to growth of your site. There are many other things you can do but I would say those are the starting points. Good luck!
There are two ways you can get traffic to your website that is 1) Search engine 2) Paid Traffic. Search engine traffic takes time, while paid traffic you can get traffic anytime you want.
There are many vays to promote your website. social networks, google adwords or any paid traffic. And sure SEO.
First of all if you are new in this field, you should take your time how online marketing works. There are lots of ebooks, training videos online that are both free and paid. You can learn a lot from studying them. Second, SEO is a surefire way to get a good ranking on google. It's not the best but I may say it is a must. Lastly, other methods such as videoblogging, email marketing or even google/facebook ads are great ways to promote your website.