I found that form IMM5710 online, but it asks me questions, that I don't know answers. Like I am applying for: A work permit with a same employer or restoration of your status as a worker ???
NOT restoration - that would mean your permit has already expired, which would make you ineligible for the BOWP.
Choose either extend with same employer, or initial/new employer. Doesn't matter, whichever is true.
What type of work permit are you applying for? ???
Open Work Permit
And they ask me for labor market opinion number, but I am applying not with it I am applying with just PR file number for extension.
"Not applicable."
And what should I put for duration of expected employment. I am already working for almost two years and willing to work there till ........
You don't need to give details of your prospective employer. Instead you can write "Bridging open work permit - Not applicable". Or you can give details if you chose, and invent a date 2 years (or whatever) into the future...
You are right, the form is not designed for BOWP applicants, but if you (1) do the online application (there's an initial questionnaire where you can indicate that you are applying for a BOWP and that you have received a "positive eligibility decision"), and (2) search this forum for the dozens of posts on applying for the BOWP, you'll do OK...