Copy Widget into Different Them

I was using a Theme that had a Widget that I really liked. I have switched to a new theme & would like to add the Widget from the first Theme into my new one. I have read many previous Support Questions & tried to follow the instructions given but I am completely illiterate when it comes to these things and can’t figure it out. Can anybody please explain in detailed steps that I could possibly understand or would anybody be willing to do this for me that knows what they are doing? Any help would be greatly, greatly appreciated. Thank you!