Add user to group

usermod -a -G ftp tony

See details on http://www.cyberciti.biz/faq/howto-linux-add-user-to-group/

Add sudoers

Edit /etc/sudoers and add this line under root account.

your_name        ALL=(ALL)       ALL

See details on https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux_OpenStack_Platform/2/html/Getting_Started_Guide/ch02s03.html

Checking uid and gid

id -u username
id -g username

See details on https://kb.iu.edu/d/adwf