Need jquery Validation help to make it wirth with jquery UI submission

Hi Experts I need your help in fixing up my jquery UI form submission validation to work with jquery Validation Plugin. Currently the Jquery UI code i am using for submission is the below:

submitUsers = function() {
    
    $('#tabs_users>#ui-tabs-2').on('click', '.submitusers', function() {
        var dataString = $("form").serialize();
        $.ajax({
            type: "POST",
            url: "save.cfm?mode=useraction" + '&submission=' + Math.random(),
            cache: false,
            data: dataString,
            success: function(result) {
                var i = result;
                $('#tabs_users>#ui-tabs-2').off('click', '.submitusers');
                if ($.trim(i) == 'Warning! Country with Same Name already Exists' || $.trim(i) == 'Warning! Code for the Entered Country Exists for another Country' || $.trim(i) == 'Warning! Code and Country already Exists') {
                    $("#AddCountry").html(result).addClass('text-warning');
                    $("#AddCountry").addClass('text-warning').fadeIn("slow");
                    setTimeout(function() {
                        $("#AddCountry").addClass('text-warning').fadeOut("slow");
                    }, 3000);
                } else if ($.trim(i) == 'Cool! Processed Successfully') {
                    $("#AddCountry").html(result).addClass('text-success');
                    $("#AddCountry").addClass('text-success').fadeIn("slow");
                    setTimeout(function() {
                        $("#AddCountry").addClass('text-success').fadeOut("slow");
                    }, 3000);
                } else {
                    $("#AddCountry").html(result).addClass('text-error');
                    $("#AddCountry").addClass('text-error').fadeIn("slow");
                    setTimeout(function() {
                        $("#AddCountry").addClass('text-error').fadeOut("slow");
                    }, 3000);
                }
            }
        });
    });
}

I want to make the validation to work with this, How can i add validation plugin to this.

My form has following fields

<form id="adduser" name="adduser">
<label>Username</label>
        <input type="text" id="username" class="input-block-level-inputfields" name="username" placeholder="Username">
        <label>Password</label>
        <input type="password" id="password" name="password" class="input-block-level-inputfields" placeholder="Password Please" />
        <label>Full Name</label>
        <input type="tel" name="fullname" id="fullname" class="input-block-level" placeholder="Your Complete Full Name" />
        <label>Password Hint</label>
        <input type="text" name="passwordhint" id="passwordhint" class="input-block-level-inputfields" placeholder="Provide Password Hint (optional)" />
        <label>Security Question</label>
        <input type="text" class="input-block-level" placeholder="Security Question" id="question" name="question" />
        <label>Answer</label>
        <input type="text" class="input-block-level" placeholder="Security Answer to the above Question" id="answer" name="answer" />
        <label>Email Address</label>
        <input type="text" name="email" id="email" placeholder="Email Address" class="input-block-level" />
        <label>Role</label>
        <select name="rolesection" id="rolesection" class="input-block-level-inputfields">
        	<option value="1">Admin</option>
            <option value="2">Staff</option>
            <option value="3">User</option>
        </select>
        <label>Status</label>
        <select name="confirmed" id="confirmed" class="input-block-level-inputfields">
        	<option value="1">Confirmed</option>
            <option value="2">Blocked</option>
        </select>
        <br />
        <input type="button" class="btn submitusers" name="sbtuser" id="sbtuser" value="Submit" onclick="javascript:submitUsers();">
</form>