To get to the 尺八演奏家 松本太郎 site, start at https://www.blogger.com (Or at https://www.google.com and click on the 9 dots in the top right-hand corner. and find Blogger down the bottom of the google services.)
Following the guide at blogspot guide
you click on the 3-line icon in the top-left-hand corner and a menu
opens on the left, like this 
To the bottom of the menu, click on the 設定 cog-wheel icon.
The Settings page that opens is long, but 2 or 3 screens down you
will see a ‘Permissions’ section like this, 
Click the 投稿者への招待状(現在返信待ち)entry and you will see
something like, 
Type in my email address, counterbean@gmail.com save, and wait for gmail to send me an email asking if I accept the invitation and for me to accept.
I will check if the email comes frequently, but because we have different schedules, it may take 1 or 2 days.
After I accept, my name and email address should appear in the entry
above the 投稿者への招待状(現在返信待ち)entry in the
ブログの管理者と投稿者 entry, like in my blog, 
Your name should be there as an administrator and my name should be there as a poster.
Make me an administrator, too and save the changes.
The process I outlined above might fail, as it is complicated. In that case, we need to troubleshoot the problem and find answers. I think we can do it.
When we get it working, I would like to upload the information about events there to see if they transfer smoothly to the yamagomori site.