Hi Peter,
If you are new to Pixinsight then – well done! It’s a bit of a learning curve but well worth it – especially for deep sky.
A good way in is with Warren Kellers book ‘Inside Pixinsight, otherwise info is scattered over the web. The early stages of calibration and stacking are well treated in videos by Adam Block (in fact all of his videos are good).
British Astronomical Association
Supporting amateur astronomers since 1890