Your first workflow

1. Create a trigger on Vendor for the Created event.
2. Create a workflow of type Trigger based, bound to the trigger.
3. Add a SendEmail action. Use tokens such as {{Reqtokens.Name}} for values from the record.
4. Save, then create a vendor. The platform publishes the record event, the trigger fires and the workflow runs.

Workflows run their actions in order. Each action's output is available to the next. See Workflows for all 26 built-in actions.