My hair is bleached white. if i want to dye it dark red, should i dye it another color first?

I have kept my hair bleached, and I would go to a salon first.

Don't do it yourself first, see what they say about doing it yourself next time. I know bleached hair is very porous and can quickly absorb. There is no way of knowing what you will get.

My hair is bleached white. if i want to dye it dark red, should i dye it another color first?

You have to fill it in with color first, and even then its going to be risky. Try using a neutral medium brown semipermanent color first, then dye it the dark red afterwards.. If you just put red over bleach it could turn an ugly pink color.