Hi $ it is a late answer but may be you are checking this site to control your question.
I am using SPSS 15 and i think that,SPSS 13 and SPSS 15 dont have many differences.
If i understand your question very well, directions must be like that =>
1. give a name to your variable. I described my variables like data, data1, data2 ...
2. [Transform=>Compute variable...]
3. Write your target data and write your calcutions. For example, if you want to calculate your data's ln, just write
ln(data) and click OK.
You'll get the results on Data Editor.