So I have a huge excel spreadsheet, with multiple lists and columns, how would I incorporate this into my SharePoint website as a new link? I know how to add an app, etc...but how do I add the spreadsheet with everything still intact with the different pages?
You upload each table as a separate list into SharePoint. However by the sounds of it this may not be the best solution as your excel document sounds quite complicated. You may have to do a bit of fiddling to get any connections and formulas right.
To export a given table into SharePoint click on the table and go to the table tab (Design) and click export > export table into SharePoint