How do I get my custom story to show up?

[Frontcannon]

<Main
Name="Testmap"
Author="A12"


StartMap=Newest map!.map
StartPos="PlayerstartArea_1
/>

This file is not valid, not at all.
StartMap and StarPos both need quotationmarks, the MapsFolder is completely missing.

This is what it should look like:

<Main

Name="Testmap"
Author="A12"
ImgFile=""
MapsFolder="maps/"
StartMap="Newest map!.map"
StartPos="PlayerStartArea_1"

/>

I don't know about the ! in your map name, it could cause problems, too.