To search for a voucher follow the navigation path:
Main Menu > Vendors > Vendor Information > Add/Update > Vendor. When you are on this screen, click on the Find an Existing Value tab. From here you will be able to search several different fields on this screen.
The SetID for vendors is UTSHR. You can click on the magnifying glass next to a field to look-up the values, or you can type in a value and click the Search button. One convenient way to search is click on the carrot next to "begins with" in several of the fields and select "contains". This will allow you to search for any characters or words in the field. To select a specific vendor from the list of Search Results, just click on the link to that vendor.