I created a YouTube video that shows how to download and do basic processing on Hubble data. Arp 273 is used as an example and basic processing is done using PixInsight AutoIntegrate.js script.
Hubble has multiple cameras and often images are taken with several filters. Before downloading other data sets you should check which cameras and filters are available for that target.
I have found these links useful:
Hubble Legacy archive is here: