There's a few ways to write "(to) smile," because there are a few different words for it.
笑って(waratte), 笑顔(egao), and 微笑み(hohoemi) all work. They all use the 笑 kanji. But! 笑って and its plain forms 笑い(warai) and 笑う(warau) can mean "smile," OR "laugh." However, 笑って by itself usually just means "smile," by itself.
笑顔 and 微笑み both only mean "smile," so you can use either one. 笑顔 is more common than 微笑み, though.
笑って(waratte), 笑顔(egao), and 微笑み(hohoemi) all work. They all use the 笑 kanji. But! 笑って and its plain forms 笑い(warai) and 笑う(warau) can mean "smile," OR "laugh." However, 笑って by itself usually just means "smile," by itself.
笑顔 and 微笑み both only mean "smile," so you can use either one. 笑顔 is more common than 微笑み, though.