Before changing anything or fetching a plugin, we are going to see if the theme can be updated. Sometimes that will be enough to make your site mobile friendly.

As you see, my theme is up to date.

The next step: You make a back-up, always make a back-up before you are going to change things or add plugins!

The best way to do this with filezilla FTP (this takes some time)

training/MarionBlack-using-filezilla-ftp