You should have provided a mockup to precisely show where you want the logo. But generally that should easily be done. I tried that with a demo installation of Cloud.
I downsized copy of the Cloud-Logo and put that here as seen from the site's root: images/logo.png
Then I added the CSS to the file templates/yoo_cloud/css/custom.css. You might alternatively set up a new Warp6 Style for this if you want.
To put the logo inside the menu bar I used this CSS:
#menu {
padding-left: 160px;
background: url(../images/logo.png) no-repeat;
}
This is a screenshot of the result:

To put the logo to the left of the menu bar, outside the main area I used this CSS:
#menu {
margin-left:-170px;
padding-left: 170px;
background: url(../images/logo.png) no-repeat;
}
This is a screenshot of the result:

The screenshots still show the default logo in the header but you might of course remove that.