How many terms of the series do we need to add in order to find the sum of the indicated accuracy?

How many terms of the series do we need to add in order to find the sum of the indicated accuracy?Let ∑_(n=3)^∞ ((-1)^(n+1))/n^4 (error<0.001).i.e. the sum from n=3 to infinity, basically i need to find a value for n which will give me the indicated accuracy.can anyone help? I dont really understand it at all to be honest....Thank you in advance.Also.