need some help concerning fb chat?

[R]

how can i show someone else on fb a conversation i was having with a mutual friend. let me explain, i was chatting with someone on fb on my computer and the person i was chatting with said some really nasty things abt another person. when i told this person what was being said about them they did not believe me so i want them to see the conversation for themselves....how do i do that
copy and paste does not work OBVIOUSLY and if ur going to suggest a method using a technical term then plse explain in detail

[TheFUZZEHNAUTS]

Copy and paste

[Milton]

You can screen cap it