Check under Settings → Interface → Skin → OSMC skin → Configure skin → Home → Customize Home Menu → [choose the home menu item you want to add a widget to] → Manage widgets → Select widget
There’s probably no visualization addon installed. This might help to get one visualization pack:
Otherwise have a look around for Kodi visualization addons on the internet and check how to install them (either via a zip file or you have to add a new addon repository to your Kodi).
