i am 13 and i want to be a singer. i have one problem i cant sight sing. do i have to learn how to sight sing just to be a singer.
To be a singer… no. To be a vocalist, especially one that is successfull and gets work, then yes, it would help tremendously!
If you go to college for a performing degree, you will be required to sight sing, and many of your auditions and all of your exams will include sight singing.
When you get to the very competitive real world, you will have an easier time getting gigs and callbacks if you can sight sing.
It's not neccesary if you skip college, but it is a skill that will help you in the long run, and the only way to get good at it is to do it a lot. Remember that as you are sight singing, the words are not as important as a) getting the right intervals between notes, b) staying in the same key in which you started, and c) the rhythms.
A good vocal teacher can help you with this. Good luck, and have fun! 