Hi, there is no predefined standard format. Just prepare an intimation letter to the employers. Introduce yourself briefly and provide details about the job fair such as the venue, date, registration process, and expected candidates to attend with their domain, qualifications, etc. You can also request employers to fill out a registration form. If you find it challenging, you can explore online options as there are plenty of resources available. Just browse and find what you need, but remember to edit it to suit your requirements.
Note: Some members of this forum might reply to you with a template using ChatGPT App, pretending as if it is their own draft.