Your questions is pretty large in scope.
Essentially you create the report in the report designer. If you do the report creation outside of .Net you will need to add the report to your .Net project.
Once you have the report, you need to add a CR report viewer to a form in your project. Then you can use code or the property tags to set the Report Source (and other functionality), which will be the name of your report in the project.
You can then run the form and the report should show in the viewer. If you are calling the form holding the CR report view object you will need to use the appropriate .Net code to make that event happen.
This is a pretty high level overview but should give you the concepts. The .Net help for Crystal Reports should give the information you need. I would encourage to get a book like Brian's .Net book as a resource since the help files are not always reader friendly.
Hope this is of some help.
Regards,
John W.