Small but steady for years

Hi everyone,
I'm new here and to the investment world. I saw 2 videos that I'm going share with you and I hope someone can guide me thro.
First: https://www.instagram.com/reel/DP40Zt1CHzl/?igsh=MWtkeDcxajU5bXE3aw==
Second:
https://www.instagram.com/reel/DSNMqiqjUPV/?igsh=MWYxcmhzdHRoeTdueA==
Basically, just small monthly contribution to reach a million or so by the retirement. I am 38 and I think I need to start anyway. I'm in Canada and I have account with TD and wealth simple.the TD agent didn't give me a real advice once he heard small contribution. So I believe that I have to do it by my own. I have 3 kids and I was thinking to do the same with each kid separately, even old enough they chose what to do. or it would be better to combine all of them under one investment account I don't know. I need to put monthly payments and whatever they make return back to the account is investment What do you suggest? Any idea will be great, also how can I focus on a certain field such as technology, AI or even gold.
Thank you