Here it gives you an overview about discovery VMware Infrastructure and the whole discovery process.
2. Some tips hopefully could help you during your discovery process in general
Search both UCMDB and CP (Content Pack) documents
In UCMDB UI, You could search jobs you want to run via Universal Discovery->Discovery Modules/Jobs->find
In UCMDB UI, After choosing one job, Discovery job details and help button could help you understand the job better.
Usually, discovery process starts with job Range Ips by ICMP, because this job's output is ipAddress and lots of critical jobs need ipAddress as input. Before you run Range Ips by ICMP, you should add ip in Data Flow Prob Setup -> Domains and Probes. Choose you probe and add ip in Ranges.
If job failed, you could check error message and it will tell you what is missing.
Just try to start discovery, Discovery job details, help document and error message would be helpful during the process.