To put a link, just click on the object on which you would like to place a link (this could be a button, picture, text... whatever you like). The properties-manager will open on top of your screen! There, please go to the "link-icon" and choose "internal" (for links inside your website) or "external" linking (for links to an other website). Then either choose the internal page required or insert the complete web-address of the external page that you would like to link!
Here is a screenshot explaining the steps:
The objects-manager is on the bottom of your screen (can be opened and closed by the little arrow on the right).