Step 1. Select the 'eyedrop' tool
Step 2. Hold down the left mouse button on your document ( make sure you have photoshop window nice and small and you can see the colour that you would like clearly)
Step 3. Drag the mouse across to the colour that you want, be it in internet explorer or whatever you want it to be in.
Step 4. Let go of the mouse and it will have the colour selected as the primary colour.
Step 5. Enjoy!
See image above for a short Gif tutorial on what it should look like.
Thanks,
-BulletsFly