I'm just starting out with squarespace too, so maybe I can help as I've gotten used to it by just googling basic functions. Here are a few links that might solve some of your questions:
Add new pages: https://support.squarespace.com/hc/en-us/articles/205814778-Adding-pages-to-your-navigation
Add text: https://support.squarespace.com/hc/en-us/articles/205813798-Text-Blocks
Add links to navigation: https://support.squarespace.com/hc/en-us/articles/205814758-Adding-links-to-your-navigation
Images: https://support.squarespace.com/hc/en-us/articles/205812888-Editing-images-on-y
