Choose a simple starting point.
A white wordmark or symbol on black makes the brightness difference easy to judge. Keep the edges clean and the smallest text readable before adding HDR. If the design only works because it glows, it needs another pass.
Use a PNG or JPEG up to 50 MB. Transparent areas in a PNG need a fill because Glowhite exports JPEG; choose black or warm white in the controls.
Find the right amount of light.
Try the Bright preset, then lower the peak brightness if it feels harsh. Highlight-only mode keeps darker areas close to their original brightness. Raise the highlight-selection threshold to target fewer pixels.
Compare the original with the HDR preview. A higher number is not automatically a better result: your display may map several settings to a similar visible brightness.
Upload. Then look again.
Download the JPEG and upload that file directly. Avoid screenshots, filters and cropping tools that may change its color information. Keep your original export so you can compare it with the published version.
On LinkedIn or any other platform, preservation of this HDR format is not guaranteed. Test the final placement on a known HDR setup and an ordinary screen. If either version looks wrong, use an SDR image for that placement.