Not able to find apt. utorrent

Can you expand the question, you are also mixing in windows applications to the question. try using laymans terms as it will be clearer

You will find torrent client in software center look for ktorrent but transmission is installed by default

Ubuntu ships with Transmission which is a great little torrent client, Ktorrent is only default in KUbuntu

If you want to use the proprietary Windows client uTorrent, there is no Ubuntu package for it (is that what you meant by "apt"?), but you can get it from uTorrent's website, and then install and run it using Wine in Ubuntu. uTorrent's developer officially endorses running it in that way. If this is what you want to do, and you have any problems getting it to work, please feel free to post again.

If you're using KDE (i.e. Kubuntu), then as others have suggested, KTorrent is an excellent program whose interface and capabilities are similar to uTorrent. Another excellent program, if you like uTorrent, is qBittorrent:
http://qbittorrent.sourceforge.net/

Unlike KTorrent, qBittorrent doesn't need KDE. I run qBittorrent on a Lubuntu system, and it serves my needs well. qBittorrent is available in Ubuntu's Universe repository, but it's a good idea to use the PPA version instead because it provides useful bug fixes:
https://launchpad.net/~hydr0g3n/+archive/ppa

Like uTorrent, qBittorrent provides maximal functionality while using minimal system resources.

In addition to being highly functional and running natively on Linux-based systems, programs like Transmission, KTorrent, and qBittorrent have the advantage over uTorrent in that, unlike uTorrent (which is proprietary freeware), they are free ("as in freedom") open source software.