I hope you have been able to follow this (longer than I anticipated) tutorial. Once you have made all the changes and saved your file remember to turn your caching program back on and delete the existing cache. Over the next week or so Google will be crawling your site and seeing the new code. Your structured errors chart (from the beginning of this tutorial) will show fewer and fewer errors... until hopefully you have zero!

Good luck to you and don't be afraid to ask questions! All themes are different, and I have made these modifications successfully on a number of them.