While this is not a bioinformatics question per se, I hope you are not actually typing

cd <my folder>

< > is a convention in unix that shows a location where a real value needs to be entered. e.g. if your directory was called test then you will type cd test so test replaces < my folder>.

It would help to spend some time learning UNIX basics. I recommend: http://korflab.ucdavis.edu/Unix_and_Perl/current.html#part1