Verb conjugation of "jubeln" in German

The current situation in Libya is really difficult. I tried to get in contact with acquaintances, but all the phones were not working. I'm really concerned about their well-being. I'll try again later.
In order to quickly become successful, one would have to change certain points, at least in my opinion: After 5 months of learning, I have still not found the grammar practice on which I should concentrate.
There are great museums if you like art. The most important is the Van Gogh museum. There are good restaurants and bars in the center, it is very international. I hope we can stay in touch.