Are you sure it's not the E363x instead of E343x? Anyway, using an instrument driver is similar to using any of the other functions in LabVIEW. From front panel terminals, diagram constants, computation results, you wire to the input terminals of the driver VI. Ouputs of an instrument driver are wired to indicators or to other LabVIEW functions. Open one of the driver VIs and turn on Context Help. As you move over the terminals and indicators of the VI, you will see an explanation of each. For example, The VISA Session of HPE3631A Application Example. A VISA session in your case would be the GPIB address of the instrument, i.e. GPIB0::5. To set the voltage of the supply, you would need to wire a numeric to this input. Look inside one of the top level VIs to see how wiring is done and how some of the lower level functions are used.
The initialize VI does a couple of things. It first creates a VISA Session to the instrument, queries the id of the instrument, and does a reset. This is typically done only once at the beginning of a program. Close is usually done only once at the end and closes the VISA session. This frees the resource.
In the LabVIEW Bookshelf, there is a document called LabVIEW Measurements Manual. You should read chapter 16 to get the basics on using instrument drivers. You might also want to check the resources at
The LabVIEW Learning Center. You can find information on classes, on-line tutorials, and books
