Download a black wallpaper to your iPhone, then open the site which can add black bookmarks to your screen in Safari on your iPhone. If it's this one, select the "Transparent" option.
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Tap the Share button at the bottom (the one with the arrow).
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Select "Add to Home Screen".
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Don't change anything here, just tap "Add".
The black icon will be added to your homescreen. You can repeat this process as often as you wish. Arrange the homescreen the way you like it. That done, set the black wallpaper as homescreen. It's better to do this after adding the icons, or else you'll have difficulties finding them.
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Hope that helps.