Comma Usage - help with example please

[caleigha]

I will be the first to admit that my comma usage is less than stellar. I am getting better, but clearly do not fully grasp it. I submitted an article and it was rejected because of comma usage. No big surprise, and I've been studying the links given in the rejection. I have made changes to my article and want to resubmit it. The problem I am having is I don't fully understand one of the comments and I'd like your help.

The original sentence was:
Visitors decide within the first few seconds of landing on your homepage whether they are going to stay, or with a quick click of a back button, leave your site.

I think the second comma should be removed, but the first is correct:
Visitors decide within the first few seconds of landing on your homepage whether they are going to stay, or with a quick click of a back button leave your site.

But the comment from the editor said:
The first comma should be after the or, not before it.

Can anyone help me understand this so I don't continue to make the same mistake again?

[Celeste Stewart]

Visitors decide within the first few seconds of landing on your homepage whether they are going to stay, or with a quick click of a back button leave your site.

Editor's suggestion:
Visitors decide within the first few seconds of landing on your homepage whether they are going to stay or, with a quick click of a back button, leave your site.

Here's one way to think of it. The phrase "with a quick click of a back button" is non-essential. If you remove it, the sentence reads:
Visitors decide within the first few seconds of landing on your homepage whether they are going to stay or leave your site.

Whenever you can omit a phrase as non-essential, the phrase should be set off with commas.

[caleigha]

Celeste - that makes perfect sense! The clouds have parted and the sun is now shining through. Thank you, thank you, thank you!