The easiest way, taught by my elementary grade teacher when I was a kid, is to press the flower like by inserting it in a book. This technique does not really retain the vibrant color and form. You cannot dry more flowers at once either.
What my grandma does with roses is air-dry them. She ties fresh flowers but not yet fully-bloomed in bunches and hang them upside down. If you have quetions regarding this, I could surely ask her and write her answers her. 🙂 I have roses in my garden but I don’t dry them. I just like them when they are fresh in the vase.