Choose the caption bubble to begin. If you want to upload a custom bubble or alternative image then submit the caption first, then edit the comment and attach a "Place img". Once the image is approved you can use it by editing the caption again.
If you're too dumb to find the large hud in the options ( one of the 3 default ones ) nobody can help you.
Small clock on top, ammo on the left, health/armor uncomfortably hugging the weaponbar, that's it.