The main idea is: SpecFlow generates fixtures for one of the common Unit-Test-Frameworks. More information you can find here.
I suppose that you loose some Item templates that appear in the Visual Studio Professional but disappear for Visual Studio Express versions. To overcome this problem you should take all templates files from SpecFlow application folder on computer where you have Professional version installed. On my computer it is located here:
C:\Program Files (x86)\TechTalk\SpecFlow\ItemTemplates
There should be the files like: SpecFlowFeature.zip and etc, all with *.zip extension. Then you should copy its to your computer for this place:
C:\Users\[User name]\Documents\Visual Studio 2010\Templates\ItemTemplates\Visual C#
And finally, open Microsoft Visual C# 2010 Express. Create console application, for example. And choose Project -> Add new item. There is only possible to open these templates with Microsoft Visual C# 2010 Express. Because inside template files it was defined that templates could be open only with C# project type.