Add static text to post URLs

if i good understand your problem, you should to go:

Dashboard -> Settings -> Permalinks and in “Common Settings” section select checkbox “Custom Structure” and here paste:

/my-blog/%postname%/

and save changes. Now refresh your page and go to random post and your url should be like:

https://example.com/my-blog/this-is-the-article-name

Good luck!