Forward regression in SPSS

#1
Hello
I am trying to predict some missing values in a dataset by doing a stepwise forward regression procedure, I was succesfull in producing an output telling me the weights (beta) of each predictor when correlated and ofcourse the collective r.
I know I am supposed to use the weights of the predictors together with the individuals scores these predictors to be able to predict the missing scores (criteria) but how do I go about doing this with this knowledge? I am mainly interested in how it is done in SPSS, but if someone could tell me how it is done manually as well that would be good for my overall understanding.
 
#2
Hey can noone help me? Can someone at least tell me how I normally would go about predicting scores in spss when I made a normal regressino analysis and got the weights and everything?