Re Adobe Acrobat .. adding comments ?

[Robert Howells]

Good Morning all,

Can somebody with the experience point me to the easiest way to
add a comment to a PDF file
        Such as a PDF file created when the Save to PDF is used
        from the Print dialogue box in OSX
I find Acrobat to be complicated to understand for a first time user.

Thanks

Bob

PS: Looked in Help file but have not found the "easy way to understand 
"  yet