It should take approximately 3 1/2 quarts. Stand the bike up straight and fill to just under the top mark on the sight glass on the left side of engine.
It is hard to give you the exact amount without know what year the bike is. A good starting point is to add about two liter of oil to the engine. Let the engine run for a few minutes to warm up. Then have a friend hold the bike straight up as you check the oil level and add oil.
It is very easy to pour engine oil to a motorcycle. Open the lid in the engine where oil can be poured. Then pour the engine oil about half a liter and then check the level by level stick or level mirror. Pour till the oil reaches the needed level.