1. First you need to create the resource. (For Example River Room). ECP -> Recipients -> Resources.
2. Once the resource is created then open up the Exchange PowerShell Tool.
3. Then type “Set-MailboxCalendarFolder RiverRoom:\Calendar -PublishEnabled $true”. This will publish the calendar with the basic defaults, such as 30 days forward and 30 days behind, availability only.
4. Then we need to know what the URL is. So we need to type “Get-MailboxCalendarFolder RiverRoom:\Calendar |fl”.

This will show our details. Such as:-