Try this:
1) Open up your Web Browser dev console (F12 in most browsers)
2) copy the code below
3) paste it into the console window and hit <enter>
4) a button will appear on this page right below your member name (where you posted the question).
5) click the button and it will display the message "test this"
var x = document.createElement("button");
x.innerHTML="click me";
document.querySelector(".member-rep-container").appendChild(x);
x.addEventListener("click", () => alert("test this!"));
Now that is hands-on learning. 😁😁