I am having trouble adding stationery to eM Client can someone help me with step by step instructions?
In eM Client this is called a template. You will find the settings in Menu > Settings > Mail > Templates and Signatures.
Have a look at the Help File (F1) at this location: https://www.emclient.com/webdocumentation/en/7.0/eMClient/Default.htm#Settings/Templates%20and%20Signatures.htm
It is from version 7, but the concept is the same.
If you have any questions after going through that, please ask.