How does one make gl jars and bottles with rudimentary tools?

I am writing a book where a teenager is stranded on an island alone and is trying to survive/thrive in this harsh environment. While barrels sealed up with tar made from tree sap is crucial for holding some things, there is an impending winter that demands gl jars to can fruit/pickled cured meat to survive. How might one go to work doing said task with the tools creatable with the items acquirable on an island?