I need to keep image button inside asp text box..is it possible

The technique you're referring to doesn't actually have the button inside the textbox normally, the border and background of the button and textbox simply blend in with a wrapper div. Here is a basic example:

<div class="wrapper">
    <input type="text" />
    <button>GO</button>
</div>

.wrapper {
    border:1px solid #000;
    display:inline-block;
}

input,
button {
    background-color:transparent;
    border:0;
}