There are two ways to link content in QSToolbox. 

One is via Related Items, which is good for internal links. 

The other way is to add a link using the rich text editor, which is available in most text fields like description, Record notes, and Document text content.  This method is good for links to external content.

Look for the 'Link' button in the text editor toolbar:

Place your cursor where you want the link to appear in the text and then click on the Link button. You can also select text for the link before you click the button.  A window will open to enter the link details:

"Text to display" is what you'll see in the text field.

The URL is the website you want to point to. It's usually best to copy and paste this in. 

Click on "Insert Link" to add the link to the text editor. 

You'll see the link is highlighted and uses the text from the "Text to display" field.

When you're done adding text, remember to save the item you're editing.