Linking Forms to another Forms

[zeidhaddad]

My Boss asked for a hard task ( for ME) which requires To create a form and inside the form create a Combo Box where i can open a drag down menu and select an option and this option Automatically fill another form Linked to this one.
For an example: Form 1 Contains the city, if i choose a specific city it will automatically update form 2 adding the region and the Post Code!

I need Help! anyone?