Futures order amount

[devops35]

I didn't fully understand futures order. For example, I will buy $5 dogecoin. I couldn't understand how to enter 5 dollars into the API. Can you help me? I think I need to set this $5 with another api request. But how and where do I do it?

By looking at the process on the web, I enter size as 1 and price as 0. In this case, it tries to do the same thing I did last time on the web.