Hi! I have a question, how do I stack my photo in Siril if I have channels L,R,G,B + Ha
You can use the mono-preprocessing script for LRGB and Ha. Once you have the individual stacked LRGB and Ha you can use the RGB Compositing tool to make a color image out of LRGB. To add the Ha you can use Photoshop and put it in screen blending mode on top of the LRGB image.