Renew old blog posts

We are looking for a writer to tweak and renew our past articles/blogs with the aim of improving our rankings while maintaining interesting and readable content.
If this is something you do would you get back to me with some information about costs and anything else we need to know please?
The login details are:
https://www.pacificinternationaltaekwondo.com.au/dojang
User: Margaret
Password: pac2020!

Thank you,
Margaret Dicks