First, rise up from engineer sit if sitted, so you're standing. To bring a console, press ` (a key with tilde ~).

You can use this console command to initiate Fly mode:
Fly

To get back to earth, enter this console command:
Walk

If you're stuck and/or want to overcome locked doors (glitches with doors happen in tutorials) - instead of entering Fly, enter in console:
Ghost

As with Fly, to get back to earth and 'materialize', enter:
Walk

Other useful console commands:
show Fog (entering it second time toggles the fog back)
DisableAllScreenMessages - gets rid of possible red warnings, for example a warning about lighting DB.