Are you asking how to stuff your external list (in TextEdit, say) into OmniFocus as individual actions? If so, here's how:
Select the whole block of text, and do Edit->Copy to copy it to the clipboard
Go to OmniFocus, either the Inbox or a specific project where you want to paste the stuff. Click on the row selection handle (the dot to the left of the checkbox) of an existing action (make a blank one first if necessary), and then Edit->Paste will insert the contents of the clipboard as individual actions. If however you are editing the action where you paste, you'll get your list inserted into the text of that action, leaving you with a multi-line action name, which probably isn't what you want in most cases.