First and most important is start demo first and triple your account 3 TIMES before you even start to trade for real. If you are using a demo account try to turn that $100 into $300 and repeat with a new account from $100 and do it again. The reason why I want you to do this is to develop discipline. There is no such thing as 'Get rich quick' (unless you are damn lucky to win the lottery).
It is definitely possible to turn $100 into $400. But first thing first, you should think about money management and risk management before you even start.
Lots of traders use 2% risk but I use 1% risk.
2% of 100 is 2
1% of 100 is 1.
You definitely don't wanna lose anything below $2.
I suggest starting out with 1 or 2 microlots.
1 microlot = 10 cents per pip
2 microlot = 20 cents per pip
So if your risk is $2, then would take 20 pips to lose that risk in 1% risk or 10 pips to lose that risk in 2%.
The 2nd thing is your profit goal, you never want to have fear or greed.
Greed will turnaround your profits into losers, and fear will cause you to gain a small profit or a loss.
You wanna try to get a goal that is realistic. Such as 'I wanna make 10 pips a day', unrealistic goals are 'I wanna make 200 pips a day'. Theses unrealistic goals are possible, only if you are really that experienced.