Crystal Report Dynamic Reports

Question

Hi, I have a grid that conatins about 40 columns and I wish to allow the user to generate a customized report with a Chart from the contant of these columns. That is, he/she may choose 3 out of the 40 columns in the Grid to generate a report. How can I have the User be able to customize the contant of his report, when it is reading from a dataset that contains 40 columns at runtime. Plus, can I give the user the option to select the type of chart to display those selected columns? That is, Bar Chart, or pie chart, etc... Many thanks in advance.