You are currently working on UAT 

Client has sent a Word file along with a corresponding sdlxliff file and wants the translation back in sdlxliff.

I just purchased SDL Trados 2019 yesterday and am feeling overwhelmed. I've just received my first SDL translation request and am not sure how to even start. I've been able to open both the Word and xliff files and I've translated the text. I now have a Word version of the translation but the client wants the xliff version. I don't know how to do this and I don't know where to look for the information. Can someone point me in the right direction?