?
(Ummm, equations do not have zeros; equations have solutions, functions have zeros, and polynomials have roots.)
I would start by using the Rational Roots Theorem, to find a root of the polynomial.
(Use your text's index, to look it up.)
Once you find a root, you know a factor, yes?
Once you know a factor, you can divide to get another factor, yes?
Once you know all of the factors, you can find all of the solutions to the given equation.
If you've learned how to divide polynomials synthetically, the whole process goes relatively quickly; otherwise, you'll need to divide longhand (which is not hard).
If you find yourself stuck trying to apply the Rational Roots Theorem, or you do not understand something I wrote, please ask specific questions, show us what you tried, or explain what you're thinking.