How to query in a sharepoint List

the following function will take an User Name as a parameter and will return the section for the user--------------------------------------------------------------


private string GetSectionByUserName(string userName)
{
string section = string.Empty;
SPList userList = SPContext.Current.Web.SiteUserInfoList;
SPQuery query = new SPQuery();

query.Query = "<Where><Eq><FieldRef Name='Author'/><Value Type='Text'>"+ userName + "</Value></Eq></Where>";

SPListItemCollection itemCollection = userList.GetItems(query);

if (itemCollection.Count > 0)
{
section = itemCollection[0]["Section"].ToString();
}
return section;
}