Add additional column to .csv using Perl.

I have a Perl script written to extract the 3rd column out of a beginning .csv file and then to place that content into a new .csv file. Now I want to take the 7th column from the original file (test.csv), add a column to new file and then input that 7th column data.

I have tested this using the splice command but only get the first column in output. Please refer to the attachment. Thanks.
textCSV.txt