You can brush your hair back into a ponytail or bun...
How to do this smoothly with natural hair?
After you have washed your hair (preferably after a hot oil/deep conditioning), use a mixture of coconut milk, a good conditioner, and a good oil and apply generously to the hair (especially the coconut milk). Your hair should be well conditioned and your natural hair should be much easier to manage and smooth.
If you still want smoother hair, apply a gel to your hair and put a scarf over your hair tightly for about 5-10 minutes. This should be more than enough to make your hair smooth enough to get into a ponytail/bun/french twist/french braid/whatever.
If the problem isn't that your hair is too poofy to get into a bun, the problem is that you have two different textures, there is no solution to that but heat or a style that disguises the textures like the above named styles and braids.