You can change the permissions of a file or a folder from its "Properties"
you access through the contextual menu you get right-clicking on it in the
file browser. You can in particular give the writing permissions to the
group. But you must already have the writing permission to change the
permissions (you can given other users access to the file you can modify).
Or, if you are an administrator of the system, you can use 'sudo chmod' in a
terminal (be careful: do NOT change the permissions of system files!). To
add ("+") for the group ("g") the permission to write ("w") permission in
/home/newlc:
$ sudo chmod g+w /home/newlc
For all the files/folders directly in /home/newlc:
$ sudo chmod g+w /home/newlc/*
For all the files recursively ("-R") in in /home/newlc:
$ sudo chmod-R g+w /home/newlc
See http://write.flossmanuals.net/command-line/moving-around/ and
http://write.flossmanuals.net/command-line/permissions/ for an introduction
to "moving around" and to "permissions".
