Like this:

Data Insertion

using (SPSite spsite = new SPSite(http://SPS01))
{
    using (SPWeb spweb = spsite.OpenWeb())
    {
     spweb.AllowUnsafeUpdates = true;
     SPList splist = spweb.Lists["Custom List"];
     SPListItem splistitem = splist.Items.Add();
     splistitem["Title"] = “Paul Joseph Adame”;
     splistitem["First_x0020_Name"] = “Luke Martin”;
     splistitem["Last_x0020_Name"] = “Adame”;
     splistitem.Update();
     }
}

Data Retrieval

using (SPSite spsite = new SPSite(“http://SPS01″))
{
    using (SPWeb spweb = spsite.OpenWeb())
    {
     spweb.AllowUnsafeUpdates = true;
     SPSiteDataQuery spsitedataquery = new SPSiteDataQuery();
     spsitedataquery.Lists = “<Lists BaseType=’0′/>”;
     spsitedataquery.Query = “<Where><Gt><FieldRef Name=’ID’ /><Value Type=’Number’>0</Value></Gt></Where>”;
     spsitedataquery.Webs = “<Webs Scope=’SiteCollection’ />”;
     spsitedataquery.ViewFields = “<FieldRef Name=’Title’ /><FieldRef Name=’First_x0020_Name’    /><FieldRef Name=’Last_x0020_Name’ />”;
     spsitedataquery.RowLimit = 10;
     DataTable datatable = spweb.GetSiteData(spsitedataquery);
     gvwList.DataSource = datatable;
     gvwList.DataBind();
     }
}