Visual webpart to fetch list data in SharePoint 2013

Hello,

Requirement :

1. Create a visual Webpart which has a dropdown box , a button and a label :

2. Data should be fetched from a list in the same site and populated in the dropdown box .

3. When a item is selected from dropdown box and clicked on the button , some data should be showing in the Label.

Issue:

I am writing the below simple code to fetch data from a list. I am getting the red squiggles as error on oSPSite andlist.GetItems(). I have added all the required namespaces and yet my SPSite object (oSPSite) is not getting recognized. Please let me know if I am missing some important namespace. PFB code and screentshot(if visible) :

using Microsoft.SharePoint;
using Microsoft.SharePoint.WebControls;
using Microsoft.SharePoint.WebPartPages;
using Microsoft.CSharp;

namespace AcronymSP.VisualWebPart1
{
    [ToolboxItemAttribute(false)]
    public partial class VisualWebPart1 : WebPart
    {
        // Uncomment the following SecurityPermission attribute only when doing Performance Profiling on a farm solution
        // using the Instrumentation method, and then remove the SecurityPermission attribute when the code is ready
        // for production. Because the SecurityPermission attribute bypasses the security check for callers of
        // your constructor, it's not recommended for production purposes.
        // [System.Security.Permissions.SecurityPermission(System.Security.Permissions.SecurityAction.Assert, UnmanagedCode = true)]
        public VisualWebPart1()
        {
           
        }

        protected override void OnInit(EventArgs e)
        {
            base.OnInit(e);
            InitializeControl();
        }

        protected void Page_Load(object sender, EventArgs e)
        {
        }

        protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
        {
            using (SPSite oSPSite = new SPSite("http://........"))
            {
                using (SPWeb oSPWeb = newoSPSite.OpenWeb())
                {
                    SPList list = oSPWeb.Lists["AcronymsList"];
                    SPListItem item =list.GetItems();
                }

            }
        }
    }
}

Thanks in advance,

Guru