chmod [who=permission] [path]
Eg:
who can be u[for user], g[for group], or o[for others]
permission can be r, w, x or a combination like rw, rwx
path is the path to the file
Shortcuts:
Add write permission for other:
chmod o+w path
Copy permissions:
If you want to give the other, the same permission that user has:
chmod o=u path
Note that chmod by numbers is binary:
User Group Others
rwx rwx rwx
Eg:
u g o
rwx rw- r–
111 110 100
Convert the binary to decimal. The following links explain how:
http://www.wikihow.com/Convert-from-Decimal-to-Binary
http://www.wikihow.com/Convert-from-Binary-to-Decimal