CM 5.8 Versions and higher

Go to:

Dashboard > Publishing > Image Library

Click on Upload Multiple

Click on Add

To upload Image 1

Click on Browse and select the image

Select the Folder

Enter a Display Name & Alt Tag

To upload Image 2

Click on Add

Click on Browse and select the image

Select the Folder

Enter a Display Name & Alt Tag

To upload more images repeat the process from Uploading Image 2

Once you have uploaded all the images click on Save.