Kathy, there’s a one-stop shopping venue for all your edification needs related to Birding By Ear for wood-warblers: earbirding.com
Here, Nathan Pieplow, an erudite sound recordist and expert birder, highlights many “ear birding” elements, including ways for you to easily read sonograms/spectrograms.

Please see his web site: earbirding.org and his recent book’s are excellent on this subject: a) Petersen Field Guide to Bird Sounds of Western N. America and b) Petersen Field Guide to Bird Sounds of Eastern N. America.

The above web site is so good that it gets a top rating from Warbler Guy’s advisory panel: me, myself, and I.

Seriously, reading and interpreting sonograms/spectrograms takes practice, but after a while you can
see the elements upon the page that originally looked like gibberish make sense.

Ergo, you’ll quickly have no problems identifying a song sparrow classic song via its sonogram in comparison to a common yellowthroat’s, and so on.

Other resources for identifying birds by sound and “ear birding” abound…..Some of my favorite are books by Dr. Donald Kroodsma, who authored the classic:
The Singing Life Of Birds.

Is warbler song easy to read on sonograms? Some people find them easier to comprehend than others. I think the above resources will help. My opinion is that some sonogram songs are easy to understand and others are more incomprehensible.