If you use WordPress.org, then making your website dual (or multiple) language is quite straightforward. (Note, these instructions do not work if you are using WordPress.com.
Firstly, check that your WordPress theme supports the languages you want to use. The easiest way to do this is to install the Loco Translate plugin. This will show you the supported languages for all your installed themes (select the “manage translations” option).
Then install the Polylang plugin – see the description here. Follow the installation guide and the getting started guide.
Now, for every page or post you create, you will see an option to select the language. Create the page/post in that language then click the + sign next to the next language you want to use and create the matching page/post for that language. If you want to match pages or posts that have already been created, just start typing the name of the page/post in the box next to the language flag. Don’t forget to create separate menus for each language too – the Polylang website has lots of useful help on this and other features.
Last, but not least, do not use machine translation to translate your page or post content. Unless you want people to laugh at you! Contact us for a high quality translation at a very reasonable price.