I used this site to learn the basics and help me to make an informed decision: Motley Fool Australia

I can’t give you any info about which apps/sites are best but I know there are practice investing sites out there where you invest in the real market with fake money to see how you go. This was many years back when I last looked at it but it was free to give it a go. Then you’d want a site/app where you can invest small amounts with low brokerage fees, which I don’t know if you can get around paying. They might actually have articles on that stuff on Motley Fool, not sure.