To create flow in salesforce, From Setup, enter Flows in the Quick Find box, then select Flows, and then click New Flow.

Drag the appropriate elements onto the canvas.

Each element represents an action that the flow can execute. Examples of such actions include reading or writing Salesforce data, displaying information and collecting data from flow users, executing business logic, or  manipulating data.

Every flow element has three settings in common:

• name,unique name, and description.

In the above example, Screen element is selected and given its general information. Then you can add field for this screen. Here we have selected Display Text.

Also you can given the field unique name (HomeScreenField). Also you can give the text information to display Hello visual flow.

In the same way you can create an another screen as well as connect them together.Then you must select which element the flow should start with when it runs.

Then save the flow.

Click run to test the flow to make sure it’s working as you expect it to and Activate the flow so that users can run it.

If you click next button the Screen 2 result will appear,

To Activate just type flow in Quick find box then select Flow and choose your created flow and click activate.To deactivate follow the same step and click deactivate.

This training information is very useful to learn about visual flow in salesforce.