Linking to documents is easy.

1. Put the page in edit mode.
2. Select the text block you want to add the link to and hit Edit Block.
3. Add some text for the link label.
4. Select that text and hit the chain icon. 
5. Pick Browse Server.
6. Upload your file. 
7. Select your file and hit Choose. 
8. Hit OK and then OK again to save the block.
9. Go back to the pencil icon to save your page changes.