Hello: How do I copy kerning from for example B’s right side, to another fonts B’s right side? Thank you 
The two B’s have the same right side, but not the left (One of them is a serif-version) …
Put the right side of both Bs into the same kerning group.
It is in different fonts, right? In Window > Kerning, click on the magnifying lens symbol and search for B on the left side. Copy what you find, switch to the other font, paste.