Concatenating files In DOS

I have a bunch of files that I need to add a single line to the beginning of. I know I can do it with “copy file1+file2 newfilename.csv”. However, I want to use “file2” with a new extension as the destination. I have tried “copy header.txt+*.aqh *.csv” but I end up with one huge “header.csv” file instead of individual *.csv files.

Any scripting guru’s that can help me out?