Workday is the primary platform for performing Financial and HR transactions at Mass General Brigham. The most common financial and supply chain applications that MGB employees use are eBuy+, eCheck, and Expenses. You can go directly into Workday or use the training found in Opus:

How to Create a Supplier Invoice Request in Workday (formally called eCheck in Peoplesoft)

https://mgb.opuseps.com/app/content/tasks/145018?doctype=0