How to Pull Information from GET API Response?

Hello,

I'm currently trying to set up automatic assignment of related assets via the SWSD API, but I am brand new to using API's and could use some help. If I have all the hardware owned by a user pulled from a GET call; how can I use this response to pull a list of all the hardware ID's? I believe I know how I would assign the hardware to the ticket, but I don't know how to use/extract the information in the response from the GET. Any help would be appreciated, thank you!