I already know some Greek given that I have a few Greek friends. I visited Greece this past summer with a Greek friend of mine and now have a growing interest. I want to learn Greek in a sense that I can communicate if I ever return to Greece next summer perhaps. What does one recommend?

I have several Greek friends named Nikki and I was wondering how you write it in Greek.
Also, what does it mean?

I have several Greek friends named Nikki, I was wondering how you write Nikki using the Greek alphabet. Thanks.
I just wanted to add, I meant using Greek symbols.