open phpMyadmin
open dolphin DB
open sys_injection
click sql and run this query

INSERT INTO `sys_injections` (`name`, `page_index`, `key`, `type`, `data`, `replace`, `active`) VALUES
('header_login', '0', 'injection_logo_after', 'php', 'replace me', '0', '1')

now edit the created row "name = header_login" and replace data field with below code replacing "replace me"

if (!isMember()) {
echo '<div style="float:right;margin-top:10px"><form onsubmit="validateLoginForm(this); return false;" method="post" action="member.php" id="login_box_form">
<table width="400" border="0" align="center" cellpadding="0" cellspacing="1">
<tbody><tr>
<td width="78">Username</td>
<td>&nbsp;</td>
<td width="78">Password</td>
</tr>
<tr>
<td width="150"><div class="input_wrapper input_wrapper_text" style="width:150px"><input name="ID" type="text" class="form_input_text"><div class="input_close input_close_text"></div></div></td>
<td>&nbsp;</td>
<td width="150"><div class="input_wrapper input_wrapper_password" style="width:150px"><input name="Password" type="password" class="form_input_password"><div class="input_close input_close_password"></div></div></td>
<td>&nbsp;</td>
<td><input name="LogIn" type="submit" tabindex="3" value="Login"></td>
<td>&nbsp;</td>
</tr>
</tbody></table>
<table width="400" border="0" align="center" cellpadding="0" cellspacing="1">
<tbody><tr>
<td width="200"><input type="checkbox" name="rememberMe"> Keep me logged in</td>
<td width="200"><a href="forgot.php">Forgot password?</a></td>
</tr>
</tbody></table>
</form></div>';
}


now hit "Go" and clear the cache and you can customize its code as per your need. simple...:)