What should I write in my thank you letter to CEO?

I have been working as R & D engineer in a company for the past 2 years during my study. I recently graduated from university and the same company hired me as a full time employee. Our CEO sent a group message congratulating me for getting my degree. I think I need to write a thank you letter. But I have no clue what to say. How should I write a short thank you letter? How can I express my acknowledgement of the help I received from the other colleagues? Here is what I prepared:

Hello CEO, Thanks for your kind words and for extending your support towards obtaining my degree. Everything I have learned in the last 2 years has been extremely helpful in achieving this milestone and I owe it to you and all my colleagues and mentors here. I look forward to our mutual success!(or Looking forward to continuing my learning journey at xyz company.) Kind regards, XYS

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