You can add notes to your collections to add information, break up links and images, or anything else you might use text for. To add a note: 

• Open up your collection by clicking on it (all of your collections can be seen on the homepage). 
• Click the green 'Edit Collection' button in the bottom-right. 
• Click the 'Aa' button
• The note box will open. Enter your text. 
• If you want to add formatting, highlight a piece of text and click the options on the top bar. You can make text bold, italicised, underlined, turn it into a heading or subheading, or turn it into a hyperlink. 
• Hit save when you're done. 

See this video for more: