User Portlet

Hello all, My name is Parisa. I am a Ph.D. student at Carleton University in Canada. I am pretty new in this community. I was wondering if you could help me to find a solution for my question. I tried to insert an input as: Y:=yb1+yb2 in the notebook, but it does not give me any out put. I also tried different ways such as: Y:=y[b1]+y[b2] Y:=y[b][1]+y[b][2] still there is no output!!! I was wondering if you could help