[packetpirate]

A couple of things to point out here. First of all, it's こんにちは.

Second, you don't need the 私の名前 part, just say 「私はクリストファさんです。」 Also, you don't use spaces when typing in Japanese.

Third, think before you get that tattoo... first of all, it's a pretty odd thing to get tattooed on you. And do you really want that? Is it something that in 30 years you could look at and still like?

And last, the only way I can think of to say that would be "私の歳は何ですか？".