how do i make my own layout for it? by that i mean it showing the keys that i pick

There is the basic ihud layout in game which you are already aware of, but what you're thinking could be an external hud which is a separate program then added in obs for streaming/recording. The most common one that I see is "NohBoard" which can be found at https://github.com/ThoNohT/NohBoard/releases although there are most likely more alternatives out there if you don't like this one.

Hope that helps!