[Spark]

Very easy to do at home. Save ya some bucks.
Make sure you have the right fluid. ATF +4. Drop the pan, clean off any old gasket, clean the magnet and change the filter. This would be a good time to add an after market drain plug to the pan so it would be easy to drain next time. Replace the pan with new gasket. No need for sealer. Gasket will seal just fine. Then refill with 4 qts. Be careful not to over fill and you want to check the fluid level after you have driven it and have it up to operating temp.
If you want to flush, you can remove the return line from the cooler circuit and put in a pan. Have someone start the car and run it until about a quart comes out, then add new back in. Repeat the process a few times until you have it flushed. You don't want to pump out all the fluid at one shot. You will know when it's flushed. The fluid will change from dark to a lighter color. Same as before, drive it till it's up to operating temp and check the fluid level.