How can I use personalization tags or tokens from the spreadsheet/Excel I upload?

You can use personalization tags or tokens in the subject or body including links and images. 

Use the drop down in the plugin to add these elements to your email.

Alternatively you can type them manually: Just add {{columnname}} (note two curly braces on each side) to the email and replace the word columnname with the name of the column you used in the spreadsheet. This works in links for example: https://example.com/?q={{email}}

It is highly recommended to check you haven't mis-typed anything by using the preview link available in the plugin sidebar.