Multisite for multi language

Hi all,

first of all I want to say happy new year to all members here.
I am ver new to wordpress and need your help.
I want to create a blog in two languages (german and english).
I decided to use a multisite installation (directory) for that.
Now I want to know how I can get a blog switcher that the user can easily switch from german to english and vice versa?
I need something like a drop down box inside the header area of my theme where one can choose the language and gets directed to the language choosen.

Thanks for any hint!