Pointing image based on coordinates

What do you mean by highlight. Do you mean a zoomed in effect

Just draw a polyLine from each of the points to the next.
You may wish to fill a polygon with a semi-transparent colour before drawing the polyline.

Here's how I do it in javascript. A quick tour of MSDN will tell you the names of the (roughly) equivalent functions in c#.

// takes a string that contains coords eg - "227,307,261,309, 339,354, 328,371, 240,331"
// draws a line from each co-ord pair to the next - assumes starting point needs to be repeated as ending point.
function drawPoly(coOrdStr)
{
var mCoords = coOrdStr.split(',');
var i, n;
n = mCoords.length;

//c.fillStyle="#aaaaaa"
hdc.fillStyle = "rgba(255,0,0,0.3)";

hdc.beginPath();
hdc.moveTo(mCoords[0], mCoords[1]);
for (i=2; i<n; i+=2)
{
hdc.lineTo(mCoords[i], mCoords[i+1]);
}
hdc.lineTo(mCoords[0], mCoords[1]);
hdc.stroke();
hdc.fill();
}