In any programming environment, if you do enough programming you will eventually want to put together code for common tasks and use it as a subroutine or a function (or whatever other name is used for that in the particular programming environment).  You can do that in LabVIEW.  Here's how.

• Choose the code that you want to "encapsulate", and select it.  (It has to be the active selection.)
• With the block diagram selected, on the menu choose Edit - Creat Sub vi.
• The code you selected will be replaced by a sub-vi.
• You will probably need to edit the connections to the sub-vi - i.e. the inputs and the outputs.
• The sub-vi comes with an icon - shown in the top-right hand corner of both the front panel and the block diagram for the sub-vi.
• You can edit the icon by double-clicking it - which brings up an icon editor.
• The icon also contains information about connectors (terminals for information flowing into the sub-vi and out of the sub-vi, i.e. inputs and outputs).  The icon may come with a single connector terminal, but you can right-mouse-click the icon to put it into a connector-editing mode to add connectors.  With a little experimentation, you can learn to adjust the configuration.
• To wire a connector, you will need either a control (for an input) on the front panel, or an indicator (for an output) on the front panel.  You can create those from the block diagram.
• To wire an output, for example, click on the terminal location on the icon (which will then turn black) and then click on the indicator (which will turn the terminal location the proper color for the kind of variable you have in the indicator).  Wire all of the inputs and outputs.
• Save your sub-vi.
• To use a sub-vi that you have created, click on the Select a vi... icon, then find your sub-vi file and select it.  You will get an insertion icon that you can use to place your sub-vi whereever you want it in your new program.