The wavelet transform can be thought of as a band-pass filter, where the location and width in Fourier space depends on the wavelet scale. Larger scales imply a lower frequency and small bandwidth.
In computing the wavelet transform, you change from small scales to larger scales. At each stage you can stop and compute the inverse wavelet transform using the remaining coefficients, while setting the small-scale coefficients to zero. You can then build up a series of smooth (or low-passed), detailed (or band-passed), or rough (high-passed) versions of your original data.
Details on computing the multiresolution analysis can be found in Lindsay et al. (1996).
Use the "Mantle convection" dataset that is included in the Wavelet sample file. This dataset contains an image of convection within the Earth's mantle.
Try the following steps: