How To: Export PNG with Transparency from Photoshop

• Highlight the area you want to KEEP e.g. a logo in the middle. I use the wizard tool to highlight the colours, then add areas using Shift and click.
  Optionally use Select, Modify: Contract (to reduce the selection within the boundaries of your logo); or Feather to soften the edges. If you use Feather, bear in mind that you’ll need to contract more.
  NB: Do NOT select the area to be transparent, but rather the area to keep.
• Add a new Alpha Channel (in Layers Window)
• Select the new Alpha Channel
• Select Edit, Clear. You should now see a blank area outline of your logo.
• Optionally set the original channel(s) to visible to see potential output: the pink area designates transparency.
• Select File, Save A Copy and check "Exclude Alpha Channels" is NOT ticked.