If you are looking for datasets from amateur astrophotographers to practice with, there are a number for useful resources.
Processing is meant to be fun! If you really need help with a particular dataset, jump on the forums or contact us directly for some pointers - even if you're just using the trial.
A long thread started by "the Elf" at Cloudy Nights, that includes datasets from the Elf himself and other CN users. StarTools processing notes can be found here as well.
The IKI Observatory is a remotely hosted astronomy setup in Castilléjar, Spain at https://www.pixelskiesastro.com/. FLO / Ikarus Imaging have sent out a setup in partnership with Optolong Filters and Starlight Xpress. The projects purpose is to provide a community based remote setup that can be collaborated on on Star Gazers Lounge - the data is made publicly available free of charge and the targets are chosen on the SGL forums.
A fantastic collection of various deep space objects, imaged in HaLRGB by Jim Misti. Working with just the L (luminance) frames, before delving into HaLRGB combining, is great way to learn the ropes.
The motion is configurable both by you and the viewer in both X and Y axes.
By cross referencing the normal image with the MaxRGB image, it is possible to find deficiencies in the colour balance.
Their operation is intuitive; is there too much red in your image?
Upon launch, the colour module blinks the mask three times in the familiar way.
You can convert everything you see to a format you find convenient. Give it a try!