This is a sample of code that I use to perform single field text searches. I use GET rather than POST in this instance but it should give you the basis to get started
//WA Database Search (Copyright 2005, WebAssist.com)
//Recordset: rsDataSet;
//Searchpage: search-form.php;
//Form: frmSearch;
$WADbSearch1_DefaultWhere = "";
if (!session_id()) session_start();
if ((isset($_GET["WADbSearch1"])) && ($_GET["WADbSearch1"] != "")) {
$WADbSearch1 = new FilterDef;
$WADbSearch1->initializeQueryBuilder("MYSQL","1");
//keyword array declarations
$KeyArr0 = array("PgTitle");
$KeyArr1 = array("PgDesc");
$KeyArr2 = array("PgDetails");
//comparison list additions
$WADbSearch1->keywordComparison($KeyArr0,"".((isset($_GET["searchtext"]))?$_GET["searchtext"]:"") ."","AND","Includes",",%20","%20","%22","%22",0);
$WADbSearch1->keywordComparison($KeyArr1,"".((isset($_GET["searchtext"]))?$_GET["searchtext"]:"") ."","OR","Includes",",%20","%20","%22","%22",0);
$WADbSearch1->keywordComparison($KeyArr2,"".((isset($_GET["searchtext"]))?$_GET["searchtext"]:"") ."","OR","Includes",",%20","%20","%22","%22",0);