First you have to learn to say "mate" correctly. At first the english speaker thinks of the work mate or companion. In spanish the word is pronounced differently. It has two silables, "Ma" and "te". The "ma" is like the "ma" in the beginning of mama. The "te" is like the "ta" in "take". Put more accent or power on the "Ma" part.
You are going to need a bombilla (metal straw) a mate cup, yerba, sugar and hot water. Make sure your bombilla is clean and that your mate cup has been prepared.
You start by adding 2-3 spoonfuls of yerba (herbs) in the mate cup. Then you add 1-2 spoonfuls of white sugar. Then fill the mate cup with hot water. In traditional Argentina they use very hot water. Carful it takes time to adapt to the heat.
Then you take a small drink and pass the mate cup to someone else. Drinking mate is a social event that should be enjoyed!