See Wiki "Family History Library Classes and Webinars". Click on this link to access Family History Library Classes and Webinars
Research in Prussian Poland by Sonje Nishimoto [This FamilySearch class describes online sources for Pomerania and other areas now in Poland].
Go to the FamilySearch Wiki and search "How to Guides"
Polish State Archives Guide: https://www.familysearch.org/wiki/en/img_auth.php/3/35/1-Polish_State_Archives-Instruction.pdf