Create a custom Web site workflow Activity
First, create a project that contains and tests the custom workflow activity.
Create a Site Workflow custom activity Item
1. Display the New Project dialog box by pointing to New on the File menu and clicking New Project.
2. Expand the SharePoint node under Visual C #, and then click 2010.
3. In the Templates pane, select Sequential Workflow.
4. In the Name box, type YunCode.WorkFlow.CustomActivity, and then click OK.
This displays the SharePoint Customization wizard.
5. Which local Web site do you want to use for debugging? Page, click Next to accept the default Web site.
This step also sets the trust level for the solution to be the farm solution (the only available option for the workflow project).
On the Specify the workflow name for debugging page, accept the default name (Yuncode.workflow.customactivity–caworkflow)
6. Change the workflow template type to site workflow, and then click Next.
7. Click Finish to accept the remaining default settings.