To get a loose curl without heat will take some time but you can try it.
You would "set" your hair.
Use "shampoo set rollers". These come in different sizes. Use the size you want. You can usually find them at a beauty supply store.
Put gel in your hair on wet hair, and roll the hair up in rollers. Let your hair dry. Make sure it is completely dry before taking it out or your curl will kick back in. Then, gently pull the curls apart and style as you like.