In general a google search of the form “fritizing part L293D motor shield” is a good starting point. This turns up a number of parts, now you only have to pick one that a) works, and b) matches the board you have. If you can’t find one or it isn’t an exact match if you post a pointer to the data for the board you have and/or a part that is almost right one of us may modify the existing part or make a new one for you.
Peter