I want frogs to come in my garden?

Hi, i really like frogs... i think there really cute because every time i go round my cousins house, there' always some there. she doesn't have a pond or anything and when i ask her 'how do you get frogs in your garden' she just says she doesn't know they just come. so how can i get them to come in my garden? i don't have a pond and i don't want to build one. Please help... Thanks xx