I can't activate my iPhone 6s

Please I am having issues activating my iPhone 6s, for over 72hrs now I ca't get over from the Hello page. This the first time that I am handling iPhone of anytime type as my own, though I bought it from some one so I don't really the os and the reast but I know its an iPhone 6s. Please someone should help me, the error message is.

"iPhone could not be activated because the activation...". Please I need help