How to make a calculator with imgui in OpenGL c++

Hi there,
I have been studying with opengl for the post few weeks. I know most of you know me and and do not like but, one of you is a idiot. And he knows who he is. He will not help, and he will comment under this. So know back to topic. 3 by 3 buttons, and a display box at the top. The thing that I last asked was how to remove the top. And that idiot didn’t help. There was a simple answer.
ImGui::Begin(“Hello”, nullptr, ImGuiWindowFlag_NoTitleBar);
Know just help me render multiple buttons beside and under each other with a display box.