Use Custom Workflow Actions in SharePoint Designer

First open your site in the SharePoint Designer and create new workflow as shown in following figure.

Then select the SharePoint list that the workflow should attached to and selects the start option of the workflow as following figure.

Now you can find the newly deployed custom action in the "Extras" category. Chose it and click the "Add" button. Then you have to specify the parameters if your custom action asked for them as follow.

Now everything is done and you can test your work flow. To do this, go to selected list and click on the arrow appear when you put the mouse on title of a list item. Then select the "Workflows" option.