What does the printer do? How do I use it?

[setro2]

  What does the printer do? How do I use it? 

[Ad Bot]

[Swollow]

you aim it at print bricks and fire it to change letters on it/pictures on it
its shown in the tutorial, try playing the tutorial

[Firecycle]

try playing the tutorial

[Greek2me]

As the above people said, the tutorial is your best friend right now. Just play through it, it only takes about 5-10 minutes.