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First, Daniel, you should have access to FTP (File Transfer Protocol or where website is hosted). For this, you will need to contact the company who created the website to request access these data: 1 - Use FTP 2 - FTP account password 3 - Port (if needed) If the website can be managed through an interface (CMS, eg Wordpress, Joomla or Custom CMS), you'll need a username and a password. In the case of a simple website consisting of HTML and CSS, you should consider the following issues: Meta Titles, Meta Descriptions, Links Anchors and Titles, Images Alts and visible content. For more information, read the Begginer Guide. If a CMS like Wordpress, you can install various SEO plugins to ease your work. Example: AllInOne or Yoast SEO Pack. It's easy to use. Have a great day! Mike.