GUI Sizing

Is everything good? I'm doing my first program in Java. How do I make it visually compatible with any monitor and resolution? I tried it once and the first time I tried it, I made the components and windows measuring on my monitor, but it looked horrible when I tried to open it in college (bigger monitor). Then I threw it all away (if I remember correctly) and decided to start from the beginning. I used Java Swing in NetBeans, but I also discontinued because of the difficulties of customizing the elements, which I wanted, but I did not know how to do it. I'm using Eclipse and decided to redo NetBeans, doing two identical programs simultaneously, to see the differences between one IDE and another (But that's not important, I think). Thanks in advance!