Add button to my dashboard

Thanks for reply.
If I want to make a button panel that send http post to a webservice i wrote,
What is the best way to acheive this?
What plugin can I use? I tried the push button with Rest call, but kept getting a Cors error that i dont allow origin headers…

Should my client use a backend plugin that will send the rest http post?
If so, what plugins should i choose? For client to communicate with backend plugin