1. Wie geht es Ihnen?

Guten tag is a typical greeting in Germany. In the morning, you would say Guten Morgen (good morning), in the evening it is Guten Abend(Good evening) and at night, you can say Gute nacht (Good night).

Beside these standard greetings, there are other greetings that Germans use, but in more informal situations, like when you talk with your friends or family. You can say Hi because many English words have found their way into the German language. A bit more German-sounding greeting would be Hallo.

When you leave, you can say Tschüss which is a very common greeting that translates to bye, or a more formal Auf wiedersehen (goodbye, until we see each other again).

Wie geht es is a common way to start a conversation. If you are in a formal situation and talk with someone unknown to you, you would say Wie geht es Ihnen?. If you talk to a friend you would say Wie geht es dir? but Germans typically shorten that to Wie geht's dir? or just Wie geht's?.

Ich bin means "I am", which is obviously a very common phrase.
Note that in the previous sentence, the question was Wer sind Sie? (who are you). Verbs in German change depending on the grammatical person. Don't worry about this right now, we will talk more about German verbs in the lessons to come.

Why is it Gute and not Guten like in previous greeting (Guten Morgen)?
Gut is an adjective. In the German language, adjectives can be used as standalone words (in this lesson gut, neu or müde) in which case the adjective doesn't change. But if you use the adjective as an attribute, it changes. We will look into adjective changes in future lessons. Don't worry about it for now.