Can you make some suggestions about how to have your voice sound smooth and not rough when you sing?
Part of what makes the voice sound smooth and connected is the quality of the vowels and they way they flow into one another. Try singing different vowels on one note: EE — AY — AH — OH — OOH. Another factor in smoothness is the way we move between different pitches. You can try singing melodies on one vowel instead of using the words; you can even slide or glissando the voice between the pitches to feel and practice a sense of connectedness and flow. Then, when you add consonants, make them as efficient as possible so they barely, if at all, interrupt the flow of the vowels and the transition between different notes in the melody.
If you’re referring to raspiness, you need to find the physical cause, whether it is dryness, fatigue, allergies, acid reflux, smoking or alcohol. When the vocal cords are healthy the roughness should go away. If not, you need to work with a voice therapist or singing teacher.