How can I edit a world with an existing Sunset Valley? - ( The Sims™ 3 Create a World Tool - Beta )

[RomerJon17]

Okay I want to edit the Sunset Valley with "The Sims™ 3 Create a World Tool - Beta".
How can I edit the existing Sunset Valley town? Not in-game =)

Thank you guys...

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The problem is I can't place any signs on the road in-game... :/

http://llnw.thesims3.com/content/global/images/caw/caw_leftgraphic_ver861816.png

[simsample]

Take a look here:
http://www.modthesims.info/showthread.php?t=447707