Use your wire stripping tool to split the cable that came with the chromecast at two points about an inch apart. Then use an x-acto knife to cut the length of insulation in half and remove it. After that, you'll have to cut/peel off the outer shielding for the cable. Then there will be a bunch of uninsulated wire, this is also the ground so just peel that back until you only have the positive, negative, and ground wire showing. Now cut all three right down the middle, and use a stripper to peel back the insulation so the three wires can be soldered later.