Whether you are working in Email or Website builder, simply drag and drop any Text based section from the available ones.
Select the part of the text you want to add your link to and click on the link icon available above.
After clicking on the link, open the Component settings tab by clicking on the little gear icon, just above the block grid. There you can add the actual URL/link in the Href field. You can also select whether you want this link to be opened in the existing or new window.