It Was Bound to Happen

Account Balance: $73,981.43.

As you can surmise from my depleted balance, my overnight position last night was unsuccessful. I placed a sell order on the EUR/USD upping the number of my lots so a margin call would be triggered before I lost too much money.
I still haven't figured out how to place proper stop losses and trailing stop losses. I did a practice run yesterday afternoon. I thought I placed a fixed stop loss at 50 pips above my entry price, and the stupid program stopped me out of my position a few seconds later. Clearly not what I wanted. The price had not gone up 50 pips, and I was utterly confused. I thought a viable alternative was to use the margin call stop loss.
My trade wasn't successful. I woke up this morning fully expecting to see my account balance hovering around $78,000. (My account balance before I went to sleep was actually near $81,000. I experimented with a few short positions, using my new specificied entry amount, and quickly earned a few thousand dollars.)
I logged into my demo account today and saw that I still had an open position. It was a position LONG in the EUR/USD. I never intended to put in a long position, especially after examining the charts. What's worse, my account balance read $73,981.43.
Turns out last night I also placed a buy order for the same amount as my sell order, thinking that would act as a stop loss. Well, you can guess what happened. My account reached a margin call before the buy order acted as a stop loss. The margin call took me out of my initial position short the EUR/USD, and the buy order acted as a buy order.
I imagine something like this was bound to happen, not because I was careless in my experimentation, but because I'm tecchnically still a beginner and I'm learning without a mentor, someone to scream "Hey, moron! What are you doing?" and act as my voice of reason.