Dialog/ HTML form to accept multi select account lookup and to create records for each Account in child entity

Here is the requirement I got. There are three entities involved here 1. Training, 2. Account and 3. Tech Support Ticket.

Whenever the coordinator creates / updates a “Training” record, and adds the attendees (“Accounts”), then records must be created for each Account with Training ID, start and end date in “Tech support tickets”. Would like to know how to display a Dialog / HTML form to collect the multi select Account, Training ID, Start and End date, then create multiple records in Tech Support Ticket with details of each account, training id, start and end date.