Dear Learner,

Hope you are doing well.

It seems you have forget to copy the file in the HDFS, that's why you are getting the error.
Please copy the file into hdfs or run pig in local mode using pig -x local command.
Also the error "Unable to load alias for iterator" comes due to the syntax error.
Use proper format to run the query and it will solve your error.

If still you get any error please let us know so that we can  help you out.
also if possible attach screen shot of the query that you execute in terminal.

Hope it resolves your query.
If you have any further query,please let us know.