About a week ago my speedometer and odometer just stopped working on my 2008 Honda Civic. So after doing some research I came to the conclusion that it was a speed sensor on the transmission. I've brought the new sensor but can't find where it's suppose to go. I've looked everywhere online but can only find how to install the sensor on older Hondas. I need to know the exact location of the sensor is on the transmission.

They are on the transaxle, typically held on by 2 bolts. If you have the replacement part, look for a similar shape with a boot and 2 wires.

Top passenger's side of the transaxle, close to the wheel well.

How exactly do I get to it?

Once you locate it, see what you can easily remove to improve access, such as an air box, etc. It's likely held in by only 1 bolt, so you should not need too much room. Be sure to coat the O-ring with ATF, prior to installation.

It is usually on the top side of the transmission... between the firewall and engine. Passenger side everyplace but where people drive on the wrong side of the road.