I've just installed Linux Mint 15 (Mate) on my laptop. I have installed Ubuntu One from the Software manager but it doesn't show up anywhere in applications and isn't found on search.
For Applications management, Linux Mint 13 has Software Manager by default. Synaptic Package Manager is also there, but most beginners prefer Software Manager (over the synaptic or command line utility).
In Ubuntu, beginners prefer - Ubuntu Software Center, it’s easy to use and it has a lot of exciting features.