If your website project will need to be published in multiple languages it is very important you install the premium language manager module after the setup of your project and before you start adding content to your website.
Go to your dashboard settings page of the project. Click the upgrade project button in the Premium Modules & Intergrations section.
When you add premium modules to your project the hosting cost will be 15€/month instead of 10€/month. It doesn't matter if you add one or all premium modules.
Select the Language Manager and click install.
Login to your project. Go to language management and add all the languages you want to add to your website.
Adding the language manager in the beginning of your project is advisable. If you didn't do this in the beginning it's better to copy content from an existing language as it will fill the pages in the other language.
You can then select which content needs to be altered. But you don't have to start from scratch.
More information about language management: http://knowledge.sitemanager.io/sitemanager-cms/language-management/add-languages-to-your-project