The CRL is not needed for first approval. It will be wrote as the first person puts in a costume to be judged. My write up is information that has been gathered from the Second Sisters Build Group on facebook (which has really great hi-res images to help you).
To submit you will need to gather your references. A 360 of the character is recommended as well as close ups of details. The level of available reference material is amazing, so they'll probably be looking for something as accurate as can be translated from a 3D game character. Once you have the outfit built, take the appropriate photos for submissions.
The Flagship Eclipse is the detachment and you can find further instruction on submission and contacting your unit here: https://databank.501st.com/databank/Join_Us