How do I toggle the build menu?

[cc\\Nox]

The next thing I'm supposed to do in the tutorial but I don't see this anywhere.

[Kurague]

B

[Glyph]

B for build, which is what the tutorial explicitly tells you to press.

[Galactician]

For future searchers..

The tutorial does tell you this, but only if you are specifically someplace you can build.

Also, on Steamdeck the control is Y.

[BodhiZafa]

You can also check the keybindings to see what it is, in case it is something other than B.