ITOM is a vast topic with separate products involved. It's better to focus first either on ITOM visibility or ITOM health based on your interest.
If you would like to learn about ITOM visibility first, take on-demand courses about CMDB, Discovery, Service Mapping and Certificate inventory & management.
If you would like to learn ITOM health first, take on-demand courses about even management, operational intelligence, AIOps and health log analytics.
Also go through ITOM pre-sales course to understand the business value which can be delivered by various ITOM products.
