Rest Assured API Testing (Java) SFTP (Winscp)

I am new to Rest Assured API testing. I have a scenario where I need to upload a file to my web application using WINSCP and use that file as attachment to post to a table in the application. In functional testing, I have used Winscp and uploaded the file which is in my D drive to the web application.

Now, I have to do api testing as well for the same scenario. So, can someone help me how to upload file using winscp or any sftp tool.

Thanks.