tranny wont shift?

[newkid17]

no it is def. reverse and first because i can only go about 10 mph... so i cant be 3rd.... i did check the big fat wireing harness that connects from the tranny and it was not snapped in all the way.... i didnt take it for a drive after i snapped it in but i still need that speed sensor reguardless.... i just need to get this thing fixed.... it has been nothing but trouble, because i was doing it on the ground in like 10 degree weather