uploaded widgets to my plugin folder, now what?

perhaps an easy question but i’m figuring this all out as i go— i uploaded some widgets into my plugins folder, but where in the wordpress admin interface should they show up so i can select them? they’re not showing up as options under appearance > widgets and the sidebar.php file doesn’t look like a reflection of what’s showing up online based on the widgets i chose in the appearance > widgets section so i’m not sure how to edit it.

does that make sense?
pointers?