A provisional application is filed to secure an early priority date for your invention. Once you have filed a provisional application you may go ahead and file a complete application within 12 months of filing the provisional application.
Please note that a provisional cannot claim priority from another provisional and for priority the earliest filing date (if it is your provisional filing date) will be considered hence it is of no use to file more than one provisional for the same invention. Of course it would make sense to file another provisional provided the content of the later application differs from the previous one.
Now that you have already filed a provisional application in the US, you may go ahead with the PCT route or Paris Convention route to claim protection for your invention in multiple countries.
Please note that the PCT application has to be a complete application.
To know more about PCT and Paris convention filing option, please visit the link http://www.invntree.com/blogs/what-are-different-patent-filing-options