Sequence diagram. What would this look like?

Hi,

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.