To begin the analysis, from the menus choose:

Analyze
 Compare Means
  Independent...

step Select $ spent during promotional period as the test variable.

step Select Type of mail insert received as the grouping variable.

step Click Define Groups.

step Type 0 as the Group 1 value and 1 as the Group 2 value.

step Click Continue.

step Click OK in the Independent-Samples T Test dialog box.