Im getting crushed by this game

I started playing it with my friends i thought i did okay/good but when i played it by myself with the CPU im literally getting fucked by them i tried doing some smart moves but i dont know what move is the fastest in hard times lol. I tried watching art of smash and i found it a little confusing of how much the small detailed moves matter. maybe i just need to get used to it and no understand some techniques i guess?

Anyways what would yall recommend?