API help: Create a new Attachment

Hello Support Team,

I am using ServiceM8's api for our add-on. I want to upload a attachment to existing job and I am using below api for the same:

but I am not sure in which param I should send attachment data also wanted to know will it accept multipart data or base64 string for data.

Can you please help me with these two queries? It would be best if you can provide any sample request in curl?