We-ell, it probably seems to AppleMan, and possibly others, that you DO really need "..10 hours of videos or 50 pages of tutorials.." ..and a good place to start is Apple's own iMovie Tutorials; there's a whole pile of them here:
http://www.apple.com/ilife/tutorials/#imovie .
You say "..I finally figured it out. You can't take the whole event into the project.." ..but you CAN. Just click anywhere on an Event (..that's any single clip in your 'Events' window..) then - as is standard throughout Apple programs - hold down the Apple ('Command') key and press the letter 'A' ..and that "Selects
All" of that clip.
You can then drag all that clip into your 'Project' window. (..Dragging, I find, is far simpler than, as you say, "..select the event, then click on the Edit button to move it to the project"..)
But you asked about audio editing. There are several ways to do what you want:
You said "..I'd like to just edit the sound out for that portion, then put in a picture (my next effort) so you can't see me coughing either.." ..If you've already got, in your Events clips, a picture - or video clip - which you want to use to "cover up" your coughing, select that Event and drag it on top of the section of clip which you want to obscure in your Project window. When you release the mouse button to drop that clip on top of the clip which you want to obscure, here's what iMovie's Help file says will happen:
(..You have looked at iMovie's Help pages, haven't you? ..Search under, for example, 'Replace'..)
Anyway, when you drag a clip from Events onto a clip in your Project and release the mouse button, this little menu pops up:
..You can then choose what you want to do with that "cutaway" clip, such as "Replace at Playhead" or "Cutaway". Using it as a "cutaway" (..temporarily cutting away to that different shot, and then coming back to the original..) will then position it above the original clip. You can then click on the little "cogwheel" icon at the start of that cutaway clip, and then, in its drop-down menu, click on 'Audio adjustments', and choose 'Ducking: Reduce volume of other tracks..' and that will reduce - to zero, if you like - the sound from the underlying original track
for the duration of that cutaway, so that your coughing disappears.
A second - and maybe simpler? - way to remove the coughing is to simply Split the video clip which has the coughing: Split it so that the sequence with the coughing ..let's say it's 3 seconds long.. becomes a separate 3-second clip. Then just click on the "cogwheel" icon at the start of that 3-second clip, and choose - as before - 'Audio adjustments', and then just drag the clip's audio level down to zero. So that you're not left with no sound at all, copy a short section of audio from elsewhere (..how? it's in the Apple Tutorials..) and paste it underneath that 3-second clip, or add music, or add an audio clip of general nondescript "ambience".
AppleMan did his best to help you. You might have offered him some thanks instead of just stamping your virtual foot and saying "..I don't need to be referred to 10 hours of videos or 50 pages of tutorials.."
He offered you help, and you spat at him. If you try a little courtesy next time; it'll get you much further.
(P.S: I see that AppleMan
already succinctly explained to you exactly how to do this in your other question called "Can the sound track be deleted from a small portion of video?" ..!)