How to give #group to an admin

css_addgroup #adminslite @css/reservation,@css/generic,@css/kick,@css/ban,@css/unban,@css/vip,@css/slay,@css/chat 80 -g
css_addadmin 76561199813590871 Xanters #css/adminslite 80 10080 -g

when i acces database group is NULL , not assigned to the player untill i set it manually in the database.

Not true, check sa_admins_flags table