After removing chunks, and before washing the item, you should allow it to soak to remove most of the stain. Combine water with 1 cup of your regular detergent and, if possible, some Borax. Allow the item to soak for approximately two hours. If some of the stain is still there, combine a small bit of water with a lot of baking soda to create a thick paste, almost like tooth paste. Rub the paste in with a sponge. Let it sit for several minutes before washing it out. Repeat if there is still a stain. Wash the item as you normally would, preferably in a load by itself.  Use detergent. If the item is white, use bleach as well. Be sure that the stain is totally removed before washing the item or it could get baked in.

How would you rephrase that briefly using Vietnamese?
Ngâm vật dụng. Làm sạch vết ố tại một vị trí bằng muối nở. Giặt vật dụng.