How to shift the frequency spectrum?
If the frequency shift that you want is a multiple of the bin spacing, as in your example, then you can easily effect the shift that you want by just rotating the FFT outputs by the number of bins that you need. In the more common case that the frequency offset is not an integer multiple of the bin spacing, then you can multiply the signal by a complex exponential function before doing the FFT.

So, if you determine that the center frequency component that you speak of is actually located at frequency $f_{offset}$ Hz in your data, and the data is sampled at rate $f_s$ Hz, then to shift the spectrum such that the component of interest is at zero frequency in the FFT output, you would do:

$$
x_{\text{shifted}}[n] = x[n] e^{-\frac{j 2 \pi f_{\text{offset}} n}{f_s}}, \ \ n = 0, 1, \ldots , N-1
$$

$$
Y_{\text{shifted}}[k] = FFT\left[x_{\text{shifted}}[n]\right]
$$