How to Change a Gu10 Halogen Light Bulb
To change a Gu10 halogen lightbulb, turn off the power switch and set up a ladder under the light fixture. Next, put on gloves so the oil on your hands doesn't damage the bulb. Press against the Gu10 lightbulb with both thumbs, then push the bulb inward and turn it counter clockwise. When the bulb feels like it won't turn any more, pull it out of the socket. Finally, place the new bulb in the socket and turn it clockwise as far as it will go.
Turn off the power switch. You really don't want to get electrocuted, right? This is the first step and probably the most important in terms of safety. Make sure that you do this before going any further. Wait for the light to cool if it only just burned out. If you don't feel any heat, it is probably safe to proceed. Set up a ladder or a chair if your light fixture is too high for you to reach. You will want to be able to comfortable move your elbows around too, it's going to be much harder to change the bulb if you are standing up on your tiptoes trying to change it using only your finger tips. Find something that will put you at a comfortable height and allows you to use both hands easily. Wear gloves. If your bulb doesn't have a protector on it, the oil from your hands can cause some serious damage to the bulb. Try to only grip it from the sides if it doesn't have a protector. If it turns out the bulb is only loose rather than burned out you don't want to risk it exploding due to the oil on your hands once you screw it back in. Press inward on the GU10 halogen bulb that is already screwed into place in your light fixture using both thumbs. Keep your grip and pressure constant on the bulb with the thumbs as you turn the bulb slowly counter-clockwise. Once it feels like it won't turn any further, you can stop pushing it inward. You should rotate it about 90 degrees. Pull the bulb straight out of the socket. Wiggle it gently as it comes out to make sure it comes out cleanly. Be careful not to drop it, especially if you are on a ladder. Remove the packaging from your new bulb. Remember to keep your gloves on as you do this so as not to get any oil from your hands on the new bulb, which would be even more dangerous and could cause it to explode in the socket if it heats improperly. Press the new bulb inward into the socket. Once you're back up on your ladder, you'll press the bulb inward into the same position that you took the old bulb out from. Twist it clockwise as far as it will go, and you can turn the lights back on! Turn off the power switch. Remember, the electricity being off is important for safety. Remove the plastic coated metal ring if there is one. There should be two plug bits on this ring if it is a specific type of halogen bulb. Squeeze them together and the ring will fall out. Use a ladder or chair if your light fixture is too high up for you to reach. Make sure you can comfortably move your arms about as this task will require some dexterity. Flatten a drinking straw and then push one end up between the rim of the light fixture and the bulb. You will want to push a good inch and a half of the straw up into the gap. You will then want to take the straw and move it around the circumference of the light bulb. You may need to do this a couple of times. For best results, treat the straw like an old fashion can opener by working all the way around the edge of the circle multiple times. You need to do this because a clip holds the wires that hold the bulb into place in the top of the light fixture.  The straw causes the clip to release the wires which allows you to grip the bulb. Remember, this isn't the case for every single GU10 Halogen lightbulb. However, if you are having troubles using your hands this could be a good solution. Unscrew the light bulb while wearing gloves. This is not as easy as it should be. The bulb's end is a white plug shaped mechanism. You will need to grab the socket in one hand and the bulb in the other. Then push the bulb (gently!) into the socket and turn counter-clockwise. Use the same techniques that you would use to open a child locked medicine bottle. Throw away the old bulb. There isn't a visible difference between a good bulb and a burned out bulb. Don't risk confusing the two. Examine the now-empty socket. See those little holes in the middle? There are four of them. You want to line the new bulb's plug so that it fits into the larger holes. Then you turn it clockwise until you feel it "snap" into place. Push the wires back up under the metal clip  (if possible). As you do this, work the bulb back into the fixture. Replace the plastic coated ring. All you will have to do is push it back in on top of the light, just like the way it was before. After that, everything should be as good as new and you'll be able to use your lights again. 
Turn off the power switch. Set up a ladder or a chair if your light fixture is too high for you to reach. Wear gloves. Press inward on the GU10 halogen bulb that is already screwed into place in your light fixture using both thumbs. Pull the bulb straight out of the socket. Remove the packaging from your new bulb. Press the new bulb inward into the socket. Turn off the power switch. Remove the plastic coated metal ring if there is one. Flatten a drinking straw and then push one end up between the rim of the light fixture and the bulb. Unscrew the light bulb while wearing gloves. Throw away the old bulb. Examine the now-empty socket. Push the wires back up under the metal clip  (if possible). Replace the plastic coated ring. 