How can i understand web designing and css??

Question

i learnt from SoloLearn, Freecodecamp, W3 schools , tried the projects made by people on SoloLearn, I practice on my own also, watch video tutorials for small projects, i don't know why i am not improving, i find it very difficult to read other people's code and it is very hard for me to build something of my own, when i write code i just use hit and trial many times and sometimes that works. i am feeling very discouraged, what else can i do to improve myself. Sometimes i am also not willing to read and understand code written by me in past, sometimes i don't want to code at all. what should i do to improve and convince myself to go into right direction.