The menu item that contains procedures to manipulate your variables is the transform menu. This menu permits you to do some sort of manipulation to your variables as you like. It provides you with some options through which you can do this. One of these options is the recode options, which gives you permission to change the value of certain variables.
For example, these options can help you in case you desired to make some changes to the system of coding that you were previously using. Another useful option under this menu is the compute option. This option gives you the chance to use the existing variables to create a new variable.
For example, if you are interested in adding or finding the average of various individual scores, which you may do when you are scoring a questionnaire, the compute option will definitely help. The shortcut to that on your SPSS is "All + t".a