Help with my Emperor Angelfish

[Makorot]

My emperor angelfish has some fin is missing and has spots on it on his pectoral fin. What is it and how can I treat it. I am a novice at this. Thanks
Makorot

 

[Deinonych]

Pictures would be helpful in diagnosis. Can you post some?

 

[Mrscribbled]

Could be a number of things. Google search, lymphocystis first to see if that matches.