Learning how to sing?

I want to learn how to sing, but I need somewhere to start. I cannot pay for lessons at the moment so I want to self teach myself. Is there some sort of sheet of music similar to tablature for singing? I don't expect myself to be pro or anything, but I just want to become at least decent.

I used to do this to warm up.

1, 121, 12321, 1234321, 123454321, 12345654321, 1234567654321, 123456787654321, 8,878,87678,8765678,876545678,87654345678,8765432345678,876543212345678.

Then again I also took free lessons.