How to sync MacBook and iPad password

I Have recently purchased a MacBook Air. I put in a 4 digit code as a screen saver and when I logged back in it asked for my password but the 4 digit code did not work and now I can't open my device. I have tried my Apple ID password and my ipad 4 digit code (not the same code) but neither works. how can I use my iPad to reset my iMac device?