It depends the size of the spreadsheet, which translates into readability.
One way is to upload a PDF into your Profile "Gear List" area.
Another way is to embed it in a Post which can be found Here.
Three basic steps, but it takes a bit of effort the first time through.
Edit: oops...wrong link fixed.
Edit2: A third way is to use Google Spreadsheets, but I can't tell you how, and then embed the link.