installing ubuntu

I just use comodo time machine for some time and now i want to install ubuntu besides win7 ,does this do any harm ?
c: pri act win7
d: pri
e: pri
f: pri
no extended and logical partitions ,and i am going to install ubuntu on f: ,the last pri partition .can i ?thanks

Yes, it will harm. CTM can’t support Ubuntu.
Booting Ubuntu will be starting the Windows file system (mounting it in technical terms) without the CTM drivers loaded. You can lose everything (or at least everything after you’ve installed CTM), render your computer invalid to boot and so on.

How can Ubuntu installed on F: start Windows’ file system on C: ?

You can’t run CTM in this conditions. Ubuntu will have access to Windows file system and, without the CTM drivers loaded (there is not a CTM for Linux yet), everything will be messed on Windows. So, dual boot system is incompatible (yet) with CTM.