Where do you type Jr or Sr if no field is given?

You can share the batch # by clicking on help at the top of your batch, click on share batch and copy paste the link or batch code here. If you check the field help, it's going to be the purple question mark above where the name would be indexed. It should tell you if you are to index jr or sr with the name.

However, Most of the index field directions will state not to add prefix and suffixes. Jr, Sr, III etc, are suffixes and should not be added in the name field. There is no place to index these suffixes.