Can't upload photos to iCloud

[clivech]

I click on the Upload icon on iCloud and it opens a dialog box. I want to upload my Photos library, which is mounted on an SD card. So I select the SD card but when it opens, the Photos Library is greyed out. (But my iTunes library is in black.) So why can't I upload my Photos Library to iCloud? Is it because it's on an SD card? Or do I have to go into Photos and upload every photo manually?