how do I insert speech into audacity I have seen others do it without a mic
If you’ve seen others do it without a mike, then the only way they could be doing so is by importing a pre-recorded audio file. Unless of course they’re using the built-in mike found in most laptops. Which is a mike, only one that’s not very obvious 
Check out the Audacity Tutorials for general advice on recording, editing and mixing audio files - http://audacityteam.org/help/tutorials