When you create a post or message, you'll have a text edit toolbar at the top of the text box. In that section, you should see a button with a chain icon.
Here's how to insert a link:
1. Highlight the text you want to make a hyperlink of.
2. Click on the chain icon.
3. Type in the URL to the website. You can also copy and paste the web address into this field.
4. When you're finished, click "Insert".