How to code it using Powershell Script?

[oemript 1]

I would like to know on how to login using PowerShell, and what wrong is following coding?

Does anyone have any suggestions?
Thanks in advance for any suggestions

 

HTML Coding

<form id="form-login" action="/login/" method="post">

<input type="hidden" value="aaabbbcccjfheh48u8jdjd" name="FORM_TOKEN" />
<input type="hidden" name="referer" value="">
<label class="mts txtRight col1 required" for="LoginForm_email">E-Mail <span class="required">*</span></label>
<input class="ui-inputText" name="LoginForm" id="LoginForm_email" type="email" />                             
<label class="mts txtRight col1 required" for="LoginForm_password">Password <span class="required">*</span></label> <div class="collection col2">

<input class="ui-inputPassword ui-inputPassword" name="LoginForm[password]"     id="LoginForm_password" type="password" />  
<button class="ui-button ui-buttonCta" type="submit">

 

PowerShell Script
$clnt = new-object System.Net.WebClient
$URL = "https://www.sample.com/login/"
$token = "aaabbbcccjfheh48u8jdjd"
$username = "sample_username"
$password = "sample_password"
$postParams = @{FORM_TOKEN=$token; LoginForm_email=$username; LoginForm_password=$password}
Invoke-WebRequest -URi $URL -Method POST -body $postParams