Log into your vSphere Web Client and click Menu – Content Library.
Click the plus sign to add a new Content Library
Add a Name and Location
Select a Local Content Library if you wish to upload ISOs, OVAs, and other templates.
Select your storage location, I use my local Freenas NFS Store.
Click Finish and your new Library will appear.
To add items, click on the Name of the Content Library, then select Actions and Import Item.
Select the item and click OK.
vSphere will then proceed to upload the item.
Once uploaded items like ISOs can be selected on the create VM Screens.