If you are interest in trading shares try e*trade, ameritrade platform. Both are oky
Try reading a book like, trading in the zone, or trading athlete.
An instrument can be either: stocks, fx, options, cfd's, etc.. all of them are instruments
Paper-trade is when you trade on paper. For instance you make a log and say you bought a stock at 600, and you are going to sell at 650 or stop-loss at 500. Then you log it down in a paper. If your strategy is right, you use it in real life.
At the moment the only demo I would really suggest is MetaTrader 4, which I am using for FX, since I find it alright. You can program it, that’s nice
Since is your first investment, try trade a demo, and then start small and go big.
Stocks require commissions, forex does not.
Forex is more risky though!
In my opinion to start trading stocks, companies like e*trade, saxo, ameritrade unfortunately will require money, and also they will give you a limitation in products / countires /regions. Unless you want to trade indices?
Why don’t you try this first!
A suggestion
I would go to Alpari or Odl and download MetaTrader 4. Have a bit of fun first of all.
And if you like trading I will then consider how to proceed? Since you have to think also if you want to be a day trader or take long term positions
Finally let me know how it will go