There is no need to input mean value and standard deviation. The purpose is to estimate the effect size which is a function of mean and standard deviation. You would need to input information on sample size and power. The output is the effect size. Note that the sample effect size is equal to the ratio of mean or mean different divided by the standard devaition, you can calculate the mean or mean difference to be the effect size multiplied by the standard deviation. But usually, effect size itself is enough.