In answer to your question, a good place to start would be with the Sticky at the top of this very forum with the title that poses the exact same question as you!
(There's a link to it in my signature.)
The other thing to say is that, contrary to gigiones' advice, forget about forex - at least for the time being. In the early days, just focus on the big picture concepts - don't worry about specific markets and individual instruments. And what are the big picture concepts? They're all covered in the sticky. Enjoy!
Welcome to this wonderful forum. You can learn a lot through this forum because there are many trading masters here. I think it would be better if we can know someone who is good at trading and then make friends with him or her, he or she may teach us how to trade, which will be perfect.
I would start by looking online at other forums, maybe see who other people refer to, forums are good like that because you will get people’s true opinions as opposed to reading reviews which could easily be biased or even written by the company itself.
The main thing to consider is if you would like a company that could give you advice or an execution only company/brokerage, I think personally if you are new to trading then a company that gives advice would be a good place to start, at least this way you will get some ideas and advice on what’s good to trade and even what to buy and when. If you go execution only then you would have to make the decisions entirely on your own, you would get research which would give you ideas (however you normally need to fund an account to get the research long term) but then ultimately the decision as to whether to buy or sell is down to you.
Either way, just have fun with it to begin with!