cant activate my new iphone 6s says activation error please update ios. what do i do ?

Well, I'm no expert at this but if you have iTunes/Finder in Mac or Windows, try pressing your phone icon in the side on finder or the top right corner in iTunes and then pressing the Software Update button. If that doesn't work, try DFU/Recovery mode to reset it from there.

parkerauto wrote:

how do i update my ios when my phone wonte activate?

click here If you can't activate your iPhone - Apple Support

Are you referring to activation with your cellular carrier? (I.e. AT&T, Verizon, etc.) If so, that issue probably needs be resolved with them and not Apple.