Content libraries are containers for VMs to use files like an ISO images or a templates.
In this blog I will create a content library, put a windows 10 template in it, version control it meaning I will have two versions the default one and one with an extra disk and upload an ISO to the content library to use.
Login to vCenter > click the three line > click Content library
Click create
Type in a name for your content library > select the vcenter you want to create the content library in > click next
Select local content library > click next
Click next
Select storage and click next
Click finish
Find your template > right click on it > click clone > select clone as template to library
Type a name for your template and click next
Select your newly created template and click next
Select your compute resource and click next
Select your storage and click next
Click finish
Go to your content library
Click your content library
Click templates tab > Click check out vm from this template
Type in a name for the template your going to modify and click next
Select compute and click next
Click finish
Add another disk to the new template
In the summary tab of the VM template click check in vm to template
Type in check in notes and click check-in
Now in the content library you should have two versions and you can delete or revert to that version
Now I will import an iso
In your content library > click the three dots where action is > click import item
Select local files > click upload file > select your iso > type a name for the item > click import
Now you should be able to access the content library from the virtual machine
Right click your virtual machine you want to attached the iso too > click edit settings > next to cd/dvd select content library iso file
Select your content library iso and click ok
Connect your cd-rom and click ok
Done