How am I supposed to "control the center" when trying to control the center is losing?

see if you can get somebody to gift you a month's worth of diamond ($13) so you can check it out... i've done 1,000 lessons & they're all excellent.

your pawns create space behind their advance almost like an advancing fence.

they also help to prevent the opponent's activity by restricting their movements (because the opponent doesn't want to trade their pieces for your pawns, they have to run away from your pawns' attacks).

your pieces (when it's possible to safely go there), can use the 4 center squares, and to a lesser extent the surrounding squares, like a launching pad.  you can attack the enemy queenside, center or kingside from the center, whereas if you launch a flank attack you're more limited.

really the best way to play at your level is just to stay solid & active & take the opponent's pieces when they mess up:

after you win one for free, start trading pieces for your opponent's equal pieces.

once you're the only one with pieces, start taking your opponent's pawns.

once their pawns are all gone, start pushing your own pawns.

make a few queens & checkmate the enemy king. 

remember these values at all times:

pawn = 1

N & B = 3

Rs are = 5

your Q = 9.

So use other resources. Lichess, for example, has lots of puzzles, lessons and videos to use and study...all free.

There's a couple of things you can do at that point, which are probably better than random moves to see what happens.  One is to look at all your pieces and pawns one by one and find any that are undefended.  Consider a move which which remedies that.  Or, if you decide you don't need to defend on that move, work out why that is OK.  A second thing to do is to flip the board around and work out a good move from the opponent's point of view.  If they have a really good move, what could you do to counter it.  A third thing which is similar to the second is that I imagine what my opponent would do if it were their turn and not mine, like if I lost a turn.  Then try to address that somehow with the move I do in fact have.  This is just advice from a beginner.