Update Notifications Plugin: Installation and Activation

I have wordpress installed on my mac and am running the gridmarket theme which needs to be updated to correct an issue.

I followed the instructions for installation of the Update Notifications plugin, but it does not show up in Plugins-Installed Plugins. The instructions alternatively suggest going to Plugins-Add New. I would prefer to do this, but I cannot find it in a search of available plugins.

I installed this plugin exactly the same way that I installed Akismet (which is in “Installed Plugins” menu and works like a charm).

Do you know the link for the plugin in the “Add New” direct download area of WordPress? Please help.

Thank you

Cara