Hi @Marie , backgrounds are indeed available for Boards but my conclusion is that they seem to be available only for ‘old’ Asana spaces. I have checked several instances and this appears to be set at the org/worksapce level (not at the user level). Spaces which were created within the past year or two appear to NOT have the option (for any users) for choosing a background image anymore, just like the screenshot by @Chad_Leo in the OP. That is what I tried to explain to them then.
I still feel the Asana guide article should be updated to inform new users that this feature is essentially deprecated, and only available to orgs/worksapces that were created before X date.