What is described here is how to process your Jupiter or Saturn files which you have previous saved as a TIFs or PNGs in AutoStakkert!2. So run Registax 6 and Click on Select and navigate your way to the folder where the AS!2 files are stored. Make sure you have the correct File of Type selected otherwise you won't see anything, then double click on it to open it. One of the nice things about AS!2 is that it centres the object you are imaging even if it wasn't centred when you captured it.
Down the left hand side you will see various options. Make sure that Linear and Gradient are ticked and leave the rest alone for now.
On the right hand side are the Functions. Click on RGB align and a little yellow box will appear on your image together with a popup window headed RGB Alignment Tool. Expand the box so that it covers the whole of Jupiter or Saturn and then click on Estimate and wait until the highlight disappears. Now click on RGB Balance and the HistoRGB_panel will appear and you should see 3 graphs showing the Red, Blue and Green components. Click on Auto Balance and they should sort of merge together. With a good image the tops of these graph should almost reach the top of the box. If not then go to the Brightness and Contrast panel and click the Brightness down arrow. This should move the lines up. And if you don't see the graph at all to start with try clicking the Brightness down arrow until you do - you might have to go down a long way before you see any lines at all but that is ok.
Now we get to the interesting bit, which is the Wavelets. For Jupiter drag each of the cursors 1 - 6 across until they read about 70 in the Preview. This should have improved the image a lot. But you can do still more is you increase the DeNoise and Sharpen options. My preferred options for Jupiter are to use 10 for all the Denoise and 130 for all the Sharpen options. With the Moon I use far less on all of them because of the brightness range, but I suggest you experiment and see what you think is best.
Having done this click on Do All and the program will implement all the options you have given it. The next step is to Save the image which it will do as a JPEG which you can then process further, if you so wish, in various editing programs. But before you do that, click on Save Scheme and give it a name like Jupiter1 - I have several schemes that I have created though nowadays I rarely any other except the one that I have described. The beauty of this is that for the next file you process all you need do is to RGB align, RGB Balance, adjust Brightness if necessary then load that scheme, click Do All and Save the image. Saves an enormous amount of time. Similarly with the Moon and Jupiter.
Of course you can also use Registax 6 to process the image right from the start, which is what I used to do until I discovered how to use AS!2. But life is too short for all of that!