how can I make this into a If/else function

Write an if/else function that goes through and labels a TipPercentage of 16 percent or more as "large" and less than 16 percent as "small". Label this new variable TipPSL Also write an if/else function that labels a party size of 4 or more as "large" and a party size of less than 4 as "small". Label this new variable PartySL.