Hi my name is Steve.
1) Are you trying to create a dual-boot machine or are you planning on ditching Windows and going with Ubuntu?
2) If you're not using a disc, how did you start the Ubuntu installation?
If you tell me a little more about what you want the end result to be, I can help you get it installed properly.
If you're going to ditch Windows, you need to put the Ubuntu installation program you download onto a CD and boot from the CD drive. Since you want to install both the Ubuntu server and desktop, you should install the server version and you can elect to install the desktop as well. Here's what you need to do. Before you ditch Windows 10:
Then, reboot your computer from the CD. When your computer starts up, look at the keys displayed at the bottom of the screen. For example, it might say Press F2 for setup and F12 for boot menu or something like that. You want to press the key associated with the boot menu. Then choose to boot from the CD drive.
PLEASE NOTE: EVERYTHING CURRENTLY ON THE COMPUTER WILL BE DESTROYED WHEN YOU INSTALL UBUNTU. THERE WON'T BE ANY WAY TO GET ANY OF THE EXISTING FILES BACK. So save whatever you need to before you start.
If I've answered your question and resolved your issue, can you please accept the answer and rate me accordingly? I don't get paid anything for helping you unless you accept the answer and rate me at least 3 stars. If not, please chat me back and I'll get you the information you need to resolve your issue. Thanks and have a great day!