You need one litre of clean water preferably boiled and then cooled. Mix in it 6 leveled teaspoon of sugar and 1/2 leveled teaspoon of salt and your ors is ready.
Make sure the mixture almost accurate. Sugar is used in this solution to help intestine absorb the salt (sodium). Too much of sugar might make the diarrhea worse or too much of salt will make your health more bad. So be sure to mix it correctly.
The juices and other such type of products usually do not help so better avoid them. Rather get a orange flavored WHO ORS and drink it over time to make up for the loss of water and electrolytes.