Hi, here are many questions about german grammar. And I know why because I am from Germany :-) German grammar is a disaster.
I found a website thats in my opinion helpful. I bookmarked it myself. It´s in german but it´s very systematic and even you don´t know german very well yet the examples can be useful.
Just have a look please. It seems elaborately? Maybe because german is elaborately. But don´t give up. Take what you need. I hope this site is helpful for a couple of you.