It's very simple to make it. And very healthy ;) You can mix all ingredients in the way you like!
Ingredients:
extra virgin olive oil, lettuce (for example iceberg lettuce), tomatoes, cucumber, black and green olives (or one of this), feta cheese.
Spices: dried oregano, dried basil, black pepper, salt (not too much).
Alternatively: red pepper, onion, garlic.
Enjoy!