To change the transmission fluid on a Honda Civic, you will need a good rug, a drip pan, 10 quarts of transmission fluid, a funnel and a ratchet wrench. First, remove the dipstick to release the pressure on the liquid. Then, remove the drain plug with the ratchet wrench. You may need to bang on the bolt with a cheater bar to loosen it. Drain the fluid into the pan. Then replace the drain plug until it is hand tight. Use the ratchet wrench to tighten the drain plug. Clean up the excess transmission fluid with a rag. Insert a funnel into the fill hole. Add the fresh fluid to the fill hole. Replace the dip stick and close the fill hole to complete the transmission fluid change.