how can I make a link in my web page text to a page, a category, a product, in the shopping cart

go to where you typed the address, highlight it and then click the hyperlink button in the little bar of icons in the text edit box. It look like a chain link with an envelope, next to the youtube button.

a box will pop up - you can choose from several options - a page in the SC, a category, a product, etc

click the insert button to save this. Now the text will be blue & have an underline. Click save