Well, the above (chown) just changes the ownership, not the access. This is a complex subject, and you should read the man page at man chmod, but a simple way to get everyone able to read and access, but not write to the file is
chmod 755 [filename]
where [filename] is the filename that you what to change. The numbers are based on adding the following values:
4 read
2 write
1 execute/traverse
and they are ordered as
user group other
This means that the user that owns the file has read, write, and execute permissions. Anyone in the group that owns the file can read and execute the file, and anyone else can read and execute the file. But I'd make sure to read the man page for chmod, as there are many other abilities as well (sticky bits, etc). Hope this helps.
