Modify Main Menu of Header

Hello,

I am quite new in wordpress and I am trying now to put a link to my main website on the main menu of the header. I can add a topic only by adding a page to my site. So, now you can see on the main menu of the header two items (on webpage https://blog.alghedi.com/): “Sobre mí” and “www.alghedi.com”. Both are pages.

I want https://www.alghedi.com or another word to be a customized link and not the link to the page created by me. I searched overall to modify the main menu of the header of Posterity, but without success.

Best
Carlos

The page I need help with: [log in to see the link]