Extensions, Codettas And Episodes

Hello, i have some troubles with the definitions codetta, extension and episode. I need to know how to construct these topics in a scherzo or minuet 

 Also, i need to see examples of literature that show me concretely this things 

Thanks. 

An episode is a developmental section of music that elaborates on previous thematic material: See any Bach fugue, the term mostly applies to that form. School project?

http://en.wikipedia.org/wiki/Fugue_%28music%29

Thank you Ken320, that's not a school project, i'm actually studying the ternary forms and i don't know how to employ these things