The first thing you need to do in order to edit the page is to click on the Edit button at the top of the page.
In order to add links, you can paste the link directly in the format http://www.yourlink.com, e.g.:
If you paste http://www.siteground.com/, the http://www.siteground.com/ URL would show up on the front page:
As an alternative you can use the [http://www.yourlink.com/ Link Name] format if you want to use a name for the link instead of direct URL. Again, taking our website as an example, it should look like this:
Adding the above code in the post would result in showing the SiteGround word on the front end which would lead to http://www.siteground.com/.