> I just tried to install the latest Ubuntu.

What source? That is - downloaded or mailed or from friend, etc.

> I can't see where it took

> I installed it within Windows.

You can not install Ubuntu within Windows. Ubuntu is NOT a Windows
program. It doesn't run under or in Windows.

> There is no Ubuntu program in Windows.

Ubuntu is a totally separate OS (Operating System). It is NOT a program.

> There is no Ubuntu on the task bar.

Ubuntu is NOT a task. It is an Operating System.

> There is nothing running other than Windows.

You can NOT run more than one Operating System at the same time. You
can run several OSs on one computer but NOT at the same time.

> I inspected the disks with Partition Magic

I don't know how you tried installing it, but you can NOT install it via
Windows. Therefore it is NOT installed and you will not find any
partitions.

> There is no .ext or other strange partition.

That is because you did not install it.

> How do I find or use Ubuntu?

You need to download the program (if you did not get a disk from some
other source) and burn it to disc.

Then place the disc in your drive and RESTART your computer. WINDOWS
should not boot up at all. Instead, Ubuntu should boot up. Then you
can use Ubuntu B*UT it is NOT yet installed. To install you need to use
the installation program on the Ubuntu desktop. Most everything is easy
after that but be VERY CAREFUL about the partitioning. You DON'T want
to wipe out your Windows installation.