I have a table that is displaying data and i have a Mass action called add to my Contact.

Just thought of this this morning: have you considered leaving the new rows you add unsaved at first? Then your new rows would show up in that nice gold italics font, easily distinguished by your users as ‘new,’ until they decide to save.

If you really want to pursue the highlighting new rows option, I’m sure someone can give you a full example, but here’s something to at least get you started:

your CSS will probably look something like:

#MyTableId tr .newrow {background: lightcoral}

In you mass action snippet, you’ll want to do something like this:

Use jQuery to find all existing rows of the table and remove your ‘newrow’ CSS class
My jquery is weak, so this is just an untested guess.

skuid.$('#MyTableId').children('<tr>').removeClass('newrow'); 

Next, get your selected items from your parent table and add them to your table, adding the CSS class ‘newrow’ to each. You’ll probably want to use $.each() to loop through all the records you’re adding.
There are plenty of examples of massaction snippets around, so you shouldn’t have trouble finding something you can adapt.