ANOVA power is affected by
The significance level
The sample sizes and number of groups being compared
The differences between group means µi
The guessed population standard deviation
You need to what alternative Ha you would consider important, detect statistically for the means µi, and to the common standard deviation σ (from similar studies or preliminary work).
The power computations then require calculating a non-centrality paramenter λ, which follows the F distribution with DFG and DFE degrees of freedom to arrive at the power of the test.