This report is probably in the details section.  Create a group, and move all the values to the group footer.  In the details section, you want to create a formula using shared variables that will append the last section together. Something like;

shared stringvar aVar := aVar + ", " + {table.field};

 

in the group footer display it by using:

shared stringvar aVar;

mid(aVar,2)  //skip the first character which is a comma.

 

in the group header, you want to reset it so that the results make sense:

shared stringvar aVar := ""

 

 

hope this helps