Proct TTEST help !

Hi Guys

I'm trying to run a independent two sample 2 test in SAS. But I can't seem to understand how to run the code:

proc ttest data=mylibname.datafilename;
class X ;
var Y;
run;

The issue is : My data has two columns with 250 entries. Column one is named Group1 and column 2 is named Group2.

What do i put in as Class and what do i put in as Var?

Entries in each group are basically time it takes to react while driving where Group 1 is those who use cell phones Group 2 is those who dont

Please help

Thanks