There are actually 3 parts to this. Aligning the beam from the tube to the head, aligning the beam so its perfectly vertical and central, and finally the red dot pointer alignment. They need to be completed in that order.
HOUSE OF LASERS TUTORIAL (quick and easy):
This method incorporates the red dot as a visual tool for alignment and many find this to be easier. If you are having difficulty with the alignment it will be best to use the OEM specified method below this video:
This tutorial may vary from the OEM recommended procedure found below so be sure to refer to all of the documentation.
OEM ADJUSTMENT DOCUMENTATION:
Aligning The Beam
The actual laser beam emitted from the tube is invisible so we have a procedure to test the alignment.
Verticality Of The Beam
This is covered in the last part of the above video
Red Dot Pointer
1.Move the laser head on the middle of the working table.
2.Place a square of masking tape over the left side of the third mirror carriage, and mark a dot on the center, like below.
3.Use the three adjustment screws on the Red Dot Pointer Mount to move red dot to the mark dot on the tape, like below.