Congrats on getting a job offer with one of the 6 employers! Your employer will know what to do as they will follow the program guide and are part of the CWP. They will know what forms to fill as they do not give you a reference letter but need to fill out forms like NBCWP-004 (you sign too). So work with your employer in ensuring the requirements are met for the job offer. You want to make sure you are "PR Ready" depending on the stream through which you are applying.
I said above - You want to make sure you are "PR Ready" depending on the stream through which you are applying.
You don’t say which stream. Go through the LINK “ARE YOU PR READY” on the NB site as there are 4 streams. Each stream will have a program guide because I don’t know which one you are applying for. This will tell you the work experience documentation required. May be different for each stream.
Congrats again on your job. You may want to post how you got the job with one of the six employers and in which NOC.