You can tell which one is considered technically correct by removing everyone except yourself from the sentence (tweaking inflections as you do so) and seeing whether it still works. "Me am from Germany" doesn't work but "I am from Germany does". As Abigail says, both sentences are used and both will be understood. But only one is correct.

Me and Jhon are from Germany Jhon and I are from Germany. Both are absolutely fine, and native speakers use them both equally. There are lot of arguments about this kind of construction, but actually they are both ok.

The second one is correct.

Grammatically, the second is correct - and Steve explains that nicely. But, in everyday conversation we tend to use both quite regularly. If I am honest, when i talk with my friends I would say John and me but in writing or in a professional situation I would use John and I. Hope that helps.