Undecided questions
I have learnt German for almost 2 months ,

Hi I suggest that you look at the Italki site for learning German
http://www.italki.com/learn-german/en-us

It can be one of three reasons:

1. You have a lousy teacher.
2. You're not studying very hard.
3. You're not very smart.

By the way, German is a hard language to learn. Give yourself time. 6 months and you'll be able to say a couple of sentences without mistakes.

I don't think German is a difficult language to learn. Compared to Finnish or Spanish, for instance, German is quite easy especially for English speakers. Do you have a good textbook for studying German? There are many good German study packages. They will give you a systematic buildup of German basics.

a.) German IS difficult.
b.) You can't express success in learning in months.
What does "Learning since 2 months" mean? One hour every day, every week ....?
Maybe your expectations at yourself are too high. My point of view is, that if you learn in a stubborn manner, you won't have much success. Take it easy ..... ;)
I'm happy with small improvements ....

practice makes perfect. 越努力越進步！

i hope you are becoming fluent soon. !

可別放棄
cheers!

Sure, German isn't quite the easiest language to learn but I think for a native English speaker it's way easier than learning Spanish or even Chinese.
The most important thing when learning a language is to actually talk in that language. You can't expect great success if you only do theoretic stuff. Go to the chat down here, for example, or buy a German novel like 'Vollidiot' by Tommy Jaud (and not one of those old ones by Goethe, Brecht, Kafka etc.). Besides school, I began learning English by playing Pokémon (the good ole days :D) with language set to English instead of German. It really helped me a lot.