Your hosting provider should give you FTP credentials. Contact them and make sure you get a host name, username, and password. Then go here: https://filezilla-project.org/ and download the FileZilla client.
When you are done installing FileZilla, open it and go to the site manager (upper left corner icon). Click New Site, type in the credentials your hosting gave you, and connect (you might have to set your Transfer mode to active). Locate the plugin on your server (/wp-content/plugins) and follow the instructions I provided earlier.
If you have any issues, Google is your friend. :) There are lots of tutorials out there.