如何使用servlet + ajax制作动态内容

I'm trying to learn jsp + servlet and everything is going well if I make it basically ( jsp send data to servlet then servlet fetch data from db and set attribute and forward to new page) but the problem occurred when I try to updating some content without reload page ( using ajax to send data to servlet and forward to jsp file and I use jquery to load specific ) , it's nothing change that content. I'm trying to learn jsp + servlet and everythin