instaling

Check this out

https://help.ubuntu.com/community/BurningIsoHowto

to make sure you're doing everything right, and then you'll need to enter your BIOS to change your boot order

http://computer.howstuffworks.com/bios.htm/printable

That should help out a bit. Burn the .iso onto a CD (don't just drag and drop), then put in the CD and restart your computer. You'll want to make sure that your CD drives are booting before your hard drives, and the install screen should show up.

i have burned the cd it shows in the my computer i click the file to open ond it asks me what i want to open it with like i said i am very new i have some experience with building but i think i have done what you suggested

If you are seeing the CD in "my computer" then you are still in windows. You need to reboot the computer with the Ubuntu CD in the drive. As long as your computer is set to boot CD first and then hard drive it will boot the Ubuntu CD and you will be able to load the live CD and explore the operating system and install if you wish. If windows loads again then your computer is not set up correctly. You will need to enter the bios setup. There are different methods depending on manufacture but pressing f2 or del when you see the computer splash screen is one common way. The computer splash screen, the one that says Dell or HP or whatever brand PC you have, only last a few seconds. There is usually a comment on the splash screen that says how to enter the bios. Do that and then edit the boot order to put CD in front of HD. Save and reboot.