how do I make a new folder and place emails in it

On any existing folder in eM Client, (Inbox, Outbox, Sent, etc.) you can click your right mouse button on that folder and a dialog box will appear to allow you to create a new folder in that specific folder.  You can repeat that process as much as you need to have all the folders you require. Of course, I imagine most would right-click on the Inbox to create sub-folders to store needed emails for later use.  That’s what I do, anyway.

From then on, any mail you receive that you wish to keep you can drag and drop into the folder you want them in.