ESD while building a new computer?
Many materials can generate electricity from friction, known as the triboelectric effect.
If you have some way to increase the humidity in the room, use it. Electrostatic charge forms much easier in dry environments, and it's winter in a lot of the world, which means lower humidity and increased risk of ESD.
Lay out all the pieces (still in their anti-static packaging) including screwdriver, screws, etc. so that you can access everything easily. You want to move as little as possible, since movement creates static. If you sit, you can't get back up until done. Getting up from a chair is a prime generator of static electricity!  If someone comes to the door, sorry, they're going to have to wait.
Take everything out of their packages, place the anti-stat packages underneath, and set them back on the table. Then follow these steps to install the motherboard:

Touch the metal case with BOTH HANDS. Seated or standing, pick one and stick with it.
Lift the motherboard from underneath the antistatic bag only, with BOTH HANDS. Lift it about one foot, then let the bag fall back to the table.
Remove one hand from the bare motherboard.
Rest the free hand on the exposed metal case.
Guide the motherboard roughly into position. Resist standing/sitting!
Finish attaching screws and whatnot, making sure you always touch the metal case before and while sticking hands inside. If you have to get up or move to the other side (can't see screws) remember to always touch the metal case FIRST. This ensures that any static which might be on your body equalizes with the entire case, so a spark can't happen when you then touch the motherboard.

Repeat these steps for the CPU, CPU cooler, RAM, video card, power supply, hard drive, case fans, etc.
CD/DVD drives already come in a metal box, so are safe as long as you don't touch their gold connectors. All external connections (USB, video, keyboard, network etc.) all have anti-static protection devices built-in, so are safe.
Good luck and happy building.