I uploaded a zipped file geodatabase into ArcGIS Online from the content menu. Now I want to see the features inside my geodatabase displayed on the map and I can't find any option to do that.
There is a thread on GeoNet that covers this process.
Open the MXD in which you have prepared your gdb layer with your symbology. Make sure only that layer is in your MXD.
1) Click on File -> Sign In... (Here you sign into your organizational account)
2) Click on File -> Share As -> Service -> Publish a service
3) As connection choose My Hosted Services (My Account) and as service name use what you want the layer to be called.
4) Under the capabilities tab uncheck "Tiled Mapping" and check "Feature Access"
5) Fill out the Item Description tab
6) Under sharing you can check who is able to see it once published
7) Click Publish in the upper right corner and it will soon show up in your "My Content" on ArcGIS Online
Now you can use those feature services in your maps.
You can do this for each file in you gdb.
You need to publish this as a hosted feature layer with your organizational account that supports publishing. https://doc.arcgis.com/en/arcgis-online/manage-data/publish-features.htm#ESRI_SECTION1_F878B830119B4443A8CFDA8A96AAF7D1