Making Animation Transition Part 1

I Have to make a transition between an animation and the main menu but I have had many difficulties. I have watched several youtube videos on how to do this but i cant figure it out. I know that i need to use the Timeline but how do I add a transition between two scenes on the timeline. Ive only worked on animation, particle systems, and camera movement so that didn't really help me. I going to keep trying and see if someone else has had the same issue.