You create a constructed list. The constructed list needs you to define a parent list. This should be the same list as the previous question list.
Use the AIC command which refers to "ADD IF CHOSEN". Sawtooth has a good help in the software to review all list commands and syntax.
If Q1 is the 1st question and you want Q2 to display only the Q1 responses selected, the following will work ...
AIC(Q1) or if you want to restrict to a range of codes (say codes 1-9), then use AIC(Q1,1,9).