If you want that your visitors dont use right click on your blog to save your page or any images then its very easy for you to disable right click option in your blog. What you have to do is add the javascript codes in your blog html/gadget

You can add the codes in two ways:
1. Add below codes in blog html below the closing head tag </head>
2. Or add these codes in layout sidebar in Html/Javascript section and save it.

Choose one of those code

With message alert:

<script language=JavaScript>
<!--

//Disable right mouse click Script
//By Maximus (maximus@nsimail.com) w/ mods by DynamicDrive
//For full source code, visit http://www.dynamicdrive.com

var message="YOUR MESSAGE HERE";

///////////////////////////////////
function clickIE4(){
if (event.button==2){
alert(message);
return false;
}
}

function clickNS4(e){
if (document.layers||document.getElementById&&!document.all){
if (e.which==2||e.which==3){
alert(message);
return false;
}
}
}

if (document.layers){
document.captureEvents(Event.MOUSEDOWN);
document.onmousedown=clickNS4;
}
else if (document.all&&!document.getElementById){
document.onmousedown=clickIE4;
}

document.oncontextmenu=new Function("alert(message);return false")

// -->
</script>

var message="YOUR MESSAGE HERE";

<script language=JavaScript>
<!--

//Disable right click script III- By Renigade (renigade@mediaone.net)
//For full source code, visit http://www.dynamicdrive.com

var message="";
///////////////////////////////////
function clickIE() {if (document.all) {(message);return false;}}
function clickNS(e) {if
(document.layers||(document.getElementById&&!document.all)) {
if (e.which==2||e.which==3) {(message);return false;}}}
if (document.layers)
{document.captureEvents(Event.MOUSEDOWN);document.onmousedown=clickNS;}
else{document.onmouseup=clickNS;document.oncontextmenu=clickIE;}

document.oncontextmenu=new Function("return false")
// -->
</script>