The water ran along the drywall seam on the ceiling. It doesn't look too bad in the photo, but I'll be repairing 3 feet of drywall (also called sheetrock.)
Taping knife if you have one, or use a wide joint/putty knife. I re-use a disposable plastic taping knife.
Sandpaper, fine grade (so you don't leave gouge marks)
Safety Glasses (wear while sanding, so airborne dust does not get in your eyes)
Disposable Paper Face Mask (wear while sanding, so you don't breathe in airborne dust)
Premixed Joint Compound (pros call it "mud")
Drywall tape (there is classic paper tape, but adhesive backed mesh drywall tape is easier to use)
Mud pan (it's long and narrow, and gives you the room you need to work the mud and load up the knife)
1. Move furniture (in this case the bed) cover it and the floor with a dropcloth and use a ladder for this repair. Solid footing is essential. No sense in getting hurt or making a mess!
2. Dig under the open seam with the putty knife to remove the paint around the damaged seam...go about 3" in each direction to create a repair area. Luckily, the damage wasn't as bad as I thought it would be and I only removed 2" on either side of the seam.
3. Sand lightly to smooth any rough bits. Adhere the tape and press it along the length of the seam.
4. If you can frost a cake, you can do this! Spread a layer of mud over the tape, and feather the mud out an inch or 2 past the repair area--let the joint dry for 24 hours. It dries light gray. Sand down any ridges. (You can buy yellow tape, and pink mud that dries white---foolproof signals to sand and paint when it's fully white...but I go with the standard white adhesive mesh tape and gray mud.)
5. Be patient--you still have to "float" or spread enough mud to cover the entire repair area, and the tape... so it's flush with the ceiling around it. Apply a 2nd coat of mud at this point.
6. Let it dry for 24hrs, then sand. If it is transitioned smoothly, you will not see shadows and imperfections when a flashlight is shone. It's worth the extra effort.
7. With a paint roller, apply two coats of Kilz primer, and let dry 30 mins. It covers very well and has a mildew inhibitor.
8. Apply 2 coats of ceiling paint...and feather the paint out for full blending with the original job. Good as new. Let it rain, let it snow!
9. With the $ you saved by not hiring a "handyman," treat yourself to some fluffy new pillows and bed linens!