I have a permanent colostomy, and a urostomy, and I didn't do any online courses either in advance of surgery or after it. This is something that is unique and different for everyone and you really learn as you go along. My stomas look nothing like pictures online anyway! You can watch as many videos and do as many courses as you choose, but reality is a whole different ballgame.
 

I learned from my stoma nurse mainly, and my partner watched and learned how to change the bags so was able to help do this when I was weak and recovering initially. Then we found tips and tricks that worked for us by trial and error.
 

As the helper/carer my advice would be to keep calm and not get flustered, never show shock or revulsion at the stoma or what it produces and be on hand initially when he comes home to help with the changing process as he will probably need assistance. Ask the stoma nurse for advice, be prepared for leakages and burst bags and be prepared to try different products to find the best to use. It's not one size fits all with this. You may also find it helpful to join Facebook stoma related groups for extra advice-I didn't feel I needed this but some people find it useful.

Oh, and invest in a mattress cover in case of leakages in the night! The thought of a stoma is worse than the reality, and getting rid of the cancer is worth it.