Beginner and need help


I am trying to learn what a sequence diagram would look like. Let say I would like to do this on a tennisgame or something like that:

Use Cases: Report Results
Preconditions: the operator with “Administrator” is logged on
Normal Flow: 1. The use case starts when adm choose to report a machresultat.
2. Adm enter the match number.
3. The system displays the players’ names.
4. Adm enter the result.
5. The system puts the winner in the match.
Alternative Flows: At 2. Both players must be completed, but not the result, otherwise
ending the use case with a error from adm.
At 4. If the result is not properly terminated the usecase with a
error from the system.
At 5. If it is the finale, no new game play, but the winner shall be printed.

What would it look like? Is there some exaples I can look at or could you show me?

I am gonna do it in ms visio.