The purpose of all punctuation is to clarify meaning. The principle use of the semi-colon is to join two related sentences. So ask yourself "If I used a full-stop, would this still make sense".
Some people write with a word processor.
Others write with a pen or pencil.
These are both grammatically complete so the work as complete sentences. But the second one refers to the first, so linking them into a single sentence with semicolon is a good idea.
You are the highest bidder.
You are to blame.
No one else.
I can't help you -- try and look for some other help.
The first two are complete sentences. You could link these with a semicolon, but they are not particularly related, so a full-stop would also be correct. The third is not a complete sentence, so a semicolon doesn't work here. It would be best to use "and"
You the highest bidder. You are to blame, and no one else.
In the last part, a dash has been used instead of a semicolon or full stop, for dramatic effect. That seems reasonable; it certainly doesn't make it hard to understand.