Library computers have Adobe Acrobat Reader, which allows you to open PDFs, highlight text, and save them with the highlights. See the "Open Computing" locations here for computers that have this software.
Adobe.com notes that Acrobat Reader is a free download.
To manage your sources all in one place, consider using a bibliographic management tool.
Zotero (recommended for undergraduate students)
Website for the National Oceanic and Atmospheric Administration (NOAA) Great Lakes Aquatic Nonindigenous Species Information System (GLANSIS)
Species Level Risk Assessments Explorer
Start here to view previous assessments on your species. You can get information for your assignment, and you can also find other articles by doing some citation searching.
For your annotated bibliography assignment, if you need help identifying what kind of reference type you have, ask a librarian.
If you find a source that you cannot access, contact the library for help. There is a free service called interlibrary loan, where we can try to get you the information you need from another library.