Nania car seat 3 in 1

Question

I'vegot a nania car seat 3 in 1 i've taken off the middle seat belt bit. but now the seat does'nt stay together, when i lift it the bottom part of the seat just falls off. the instuctions are on the side of the seat which does'nt really help. it just tell u how to put the seat belts, on the seat.i need to know how to keep the car set together. thank 4 ur help.