Dynamic Placeholders marketplace module throws method definition error

Question

This is my first time with Dynamic Placeholders and having a hard time getting started.

I have installed the package from here
https://marketplace.sitecore.net/en/Modules/I/Integrated_Dynamic_Placeholders.aspx

and trying to render a component as

@Html.Sitecore().DynamicPlaceholder("section")

When browsing the page in preview mode, the error is

    Sitecore.Mvc.Helpers.SitecoreHelper' does not contain a definition for 'DynamicPlaceholder and   
  no extension method 'DynamicPlaceholder' accepting a first argument of    
  type 'Sitecore.Mvc.Helpers.SitecoreHelper' could be found (are you missing 
   a using directive or an assembly reference?)

'

If I just say, @Html.Sitecore().Placeholder("section"), it works fine.

Using Sitecore 8.2 with MVC

SOLUTION:

Patrick Barron's answer worked. There are two parts to it:

In the /Views/web.config include the namespace

<add namespace="SitecoreExperienced.SitecoreControls" />

, and in the content editor, when adding the controls, append "_scexp1" to the placeholder name. eg:

1st Rendering: widgets
Placeholder key : section

2nd Rendering: banner
Placeholders : section_scexp1

3rd Rendering: banner
Placeholders : section_scexp2

Answer 1

From the error message, it sounds like the DLL for the Dynamic Placeholder isn't a known reference for your views. You'll want to add the following line to your /Views/Web.config file in your view folder:

<add namespace="SitecoreExperienced.SitecoreControls" />

To should look something like:

<system.web.webPages.razor>
<host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=5.2.3.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
<pages pageBaseType="System.Web.Mvc.WebViewPage">
  <namespaces>
    <add namespace="System.Web.Mvc" />
    <add namespace="System.Web.Mvc.Ajax" />
    <add namespace="System.Web.Mvc.Html" />
    <add namespace="System.Web.Routing" />
    <add namespace="Sitecore.Globalization"/>
    <add namespace="Sitecore.Mvc" />
    <add namespace="Sitecore.Mvc.Presentation" />
    <add namespace="System.Web.Routing" />
    <add namespace="SitecoreExperienced.SitecoreControls" />
  </namespaces>
</pages>