I don't have Acrobat and I need an editor to make notes on the PDFs of class notes I download. Any good, reliable, free ones out there?

I highly recommend FoxIt Editor. Its actually pay software, but you can download it for free and it'll let you do everything, but will put a watermark on every page unless you buy the full version.

http://www.foxitsoftware.com /pdf/editor/

The foxit reader is also way better than acrobat reader and is completely free.

I agree, Foxit is a very good pdf viewer/editor. But if you want a free pdf editor with no watermarks after editing, get Pdf Xchange Viewer. The portable version takes up only ~ 4 mb, but resource usage is larger than Foxit's...not that anyone would care lol

Here's a direct link for download!

is there anything for a mac computer, because it seems the zipped file can't be open by the computer even after i unzipped it.

yeah pdf xchange viewer is for windows only
however i know that Preview can add text & photos to pdf files
if not you can always use www.pdfescape.com