Only playing against npc

I just tried online friendly competition first time and I gave up after second turn after opponent summoned 2 2500 attack and stole my monster with trap card in second turn. Last time I played yu gi oh was 2016 when insect and water character was the meta and Pegasus relinquish was op. How do people keep up with attack and defenseI. I didn't know what was going on and didn't have time to read the card effects. I immediately closed app on my turn