wont go into gear help!

[p1end1]

Hey guys im new here i have 2001 f250 7.3 powerstroke 4x4 and i was driving along and stopped at a light and when i went to take off the truck had to rev to approx. 2400 rpm before it would move so i stopped at the nearest place and checked fluis levels and eveything was normal...if i put it in reverse it opperates normale but in D and 2 and 1 it doesnt do anythhing except rev up until i let off throttle then its attempts to go into gear and seems to slip right back out..i just got the truck about a month ago and first deisel ive ever owned so kinda lost i dont have a and check engine lights or anything on....any help would be veryyy appreciated