Hello.
I see now. So the problem is that you don´t have a link to
CMS Desk on your site. Well, you can add proper web part on your page and display these links (to CMSDesk and CMSSiteManager), or you can open it manually.
If you want do it via web part, you can use Static text web part with following code:
<div style="border: 1px solid #cecfce;background:#f7f3ef;color:#555555;font-weight:bold;padding: 3px;font-size:10px;text-align:center">Sign in to <a href="~/CMSPages/logon.aspx?ReturnUrl=~/cmsdesk/default.aspx&username=administrator">CMS Desk</a>. Sign in to <a href="~/CMSPages/logon.aspx?ReturnUrl=~/cmssitemanager/default.aspx&username=administrator">CMS Site Manager</a>. The default account is administrator with blank password.</div>
(please note I used example class, which can be changed according to your needs).
If you choose manual approach, you can access CMSDesk like domain.com/CMSDesk (just add /CMSDesk after your domain name).
Best Regards,
Radek Macalik