Page by tags with no plugins

I wanted to have a menu voice in the top bar for listing all the post tagged with particular word.

You can do it easily without the need of external plugins just by going to:
Appearance>Menus>Links

and adding the url that automatically searches blog posts based on a particular tag, and then add it to the menu and check the menu sections like shown in this image.

Schermata 2013-04-27 alle 19.45.05

Hope it helps.