The sun can be detrimental to tattoos. The uv rays will cause the pigment of the tattoo to fade and cause your skin tone to deepen making the tattoo fade.
If you just got your tatoo yesterday I really do not recommend having your tatoo out in the sun uncovered. The sun is not good for tatoos period. When you expose your tatoo to the sun it will begin to fade it and will continue to do so.
Keep your tattoo out of the sun until it is completely healed. Even a healed tattoo should be protected by 30 SPF or higher sunblock. The sun will fade and damage a tattoo very quickly, even after it's healed. Exposing it now will make it look horrible. Follow the aftercare instructions you should have been given at the tattoo parlor.
Tattoos are very sensitive to sunlight. You always want to put sunblock on over your tattoos, but since you got it yesterday, you cannot, so you should cover it up.
