Change text from "Submit" on input tag

The value attribute on submit-type <input> elements controls the text displayed.

<input type="submit" class="like" value="Like" />

The value attribute is used to determine the rendered label of a submit input.

<input type="submit" class="like" value="Like" />

Note that if the control is successful (this one won't be as it has no name) this will also be the submitted value for it.

To have a different submitted value and label you need to use a button element, in which the textNode inside the element determines the label. You can include other elements (including <img> here).

<button type="submit" class="like" name="foo" value="bar">Like</button>

Note that support for <button> is dodgy in older versions of Internet Explorer.