To access reports, click on Reports in the left side menu:

Select the report type you want to convert from by using the dropdown menu in the upper left corner, and use the date filtering options to find the report. Usually users have a type called Offer they convert reports from: 

Changing the status
If you don't use Statuses in SalesScreen, you can skip to Converting the report.

To change the status, click the status field for the report, select the desired status for the report and click Save changes in the bottom right corner:

Converting the report
Click the three dots in the rightmost column for the report, and select Convert:

You will now see a form where you can select the desired Type and Product and click Add report: