Ratin,
Several ways:
1. Use the VI Library Manager (Tools menu). You can navigate to a list of VIs on one side, a VI library on the other, and copy one or more of the VIs into the library that way.
2. For an individual VI, just choose Save As, select the target VI library to save into, and save.
3. You can do it programmatically from LabVIEW if need be.
--John
