zeroing out unused hard drive space [running be4 for g4u]

Hard drive imaging tool,g4u's, webpage recommended running of these programs ... #shrinkimg
Now the other ones dont work... get to around 180-240GB on my 300GB hard drive and they get a blue screen so id figure to try and see if Eraser can do it without Windows kernel erroring and complaining.

I was wondering how to do zero all unsuded space....

My best guess is New Task-> Unused space on drive ->C:

Edit ->Preference->Erasing->New ->Pattern Byte1 00000000
and not sure but maybe choose Bytes 2 and 3 as well? and set them to 00000000.
Click okay...

Now then select/highlight that method (so now its the default method to run when u run each new task)

Back at main screen, run the Task...

now the Bytes part is what confused me, otherwise i think its mostly right, Right?
I also want to know how to properly create a method for overwriting free diskspace with zeroes! Im using v5.82. Thanks in advance for any help!
You need to add a new wipe option. So in eraser:

edit -> preference -> erasing -> unused disk space

add "new" pattern. Give is a name, eg "zero" click add and it will automatically add a zero pattern. then save it. Once saved. Highlight "zero" on the unused disk space to select this option for future wipes.