If you right click a topic in Project Manager there will be a Duplicate Topic option. In some older versions it doesn't work too well and you haven't said which version you are using. Please start threads with that information.
Once you have created the topics, you can drag and drop them into whatever folders you want. Sorry but it is a one by one task.
The other way might be to try this with a copy of your project.
Create an English folder and organise all your existing topics under that.
Create a French folder and close RoboHelp.
Using Windows Explorer copy the contents of the English folder into the French folder.
Open the copy RoboHelp project. Right click the French folder and select Import. You will be able to import all the topics in any one folder in one go.
It's worth a try but remember, you do this in a copy.
See www.grainge.org for RoboHelp and Authoring tips
Sorry for the missing info: I have RH9.
I am trying to avoid having to copy each topic one by one. I'll give a try to Peter's suggestion to create a folder and then import. I tried it, but it doesn't allow me because of Robosource control. I'll remove the copy from the source control and try it again.
Thanks so much for all your valuable tips and tricks. What would I do without you?
I just had to get my project out of source control, create my French folder, and put it back in.