Hi aslam
Here i attached sample footprint for you (check page no 256 in your datasheet).
1) open your PAD designer (cadence-->PCB utilities-->pad designer-->select Layer mode-->select shape as rectangle in downside )after that select TOP,solder mask,paste mask for SMD Package,enter the width and height of the package as mention in rectangle box in image file.{if it is Through hole component You have select Following layer (TOP,default inner,bottom,solder mask top and Bottom)}. save the file in your location.
2)open PCB editor after that-->file-->new-->select the directory and then select file type as package symbol. so your footprint should be saved in .dra format for example SOIC-28pin.dra,
after that setup-->user preference-->library-->psm path and pad path (give your pad saved location ).
3)layout-->pin.select your pin name from pop-up window.place the pin in origin.in command window (x 0 0){make sure your drawing unit as mm or mil}
4)copy that pin from edit-->copy in find option select pin after that use command window x 26.3779 after that ix 26.3779 like that create.
5)assemply top,silkscreen top,place bound top need to use.package height need to mention.
if you have more doubt send mail to me
kabaleevisu@gmail.com