Outlook add folder inside a subfolder

I use the code to create a subfolder inside “Inbox” folder in outlook.

f_oapp.Session.DefaultStore.GetRootFolder().Folders
AND
f_oFolders(“Inbox”).Folders.Add(DateTime.Now.ToString(“yyMM”),Type.Missing)

But I am not sure how to create other three folder inside the subfolder that I have created. Would someone can help me for that?