Newbie with ST - help needed on how to issue JSON call

I am completely new to SmartThings. I want my SmartThings hub to make a JSON post request to an external server when my cell phone comes home. Currently this triggers the coming home automation but I can’t even figure out where to get started on connecting this to a post request. Can someone give me some pointers on how to get going? Thanks.

Why not define your cell as a presence sensor, either native, or through some service like life360?
Otherwise build a smartapp that is using functions like httppostjson. You can find more info in the developers documentation through the ide.

Thanks, I got that far - and I also am using IFTTT to send a trigger to the remote server. However, I was thinking a direct HTTP call would be quicker than IFTTT as it can run into the minutes and even hours. Is there no generic ability to trigger an HTTP call from the SmartThings app? Thanks.