You will need software that can open a Spreadsheet in the XLSX format. A free to use option is LibreOffice.
Everyone gets frustrated with paying Credit cards and not getting anywhere because of the interest charges. What if instead, you could collect those interest charges yourself as savings? Here is a spreadsheet that will help you do just that. You can either use 100% of your payment towards the balance or save the interest into your savings account. This is possible because everything is controlled by you. Use your accounts and debit card. Set your interest rate as high or low as you would like. I have a blog post explaining how to use it. This Blog Post explains how to use this file.