aggregate functions how to count a column and return the value in the same query

I am trying to learn how aggregate functions work in SQL and I cant work out how to calculate the number of times a value appears within a query.

Im using MSSQL 2008 and everything I try seems to cause an error.

Below is my query:

SELECT category, 
       template, 
       galleryshortDescription, 
       galleryLongDescription, 
       GalleryName,   
       GalleryTitle, 
       GalleryID, 
       GalleryCreatedDate, 
       GalleryLastUpdated, 
       GalleryPublished, 
       GalleryViews, 
       ObjectID, 
       GalleryDescription, 
       HtmlMetaKeywords, 
       HtmlMetaDescription

FROM dbo.ImageGallery

I would like to return the category field as well as the total number of times it appears in this query and I have tried using

count (category) AS category_counter

any suggestions greatly appreciated

thanks in advance