[ubuntu] Missing characters while installing ubuntu(14/15) and other errors.

I´m 100% new to ubuntu.
I have tried installing ubuntu on other machines and it have worked.
A while ago I wanted to try ubuntu on my main machine but I could not get the installation to look like it should(problem to get my pc to boot from the disk and missing letters).
This time I ran the disk while windows 10 was ruing and I got a window pup-up which I used to install some sort of "launch from the disk" help software and I rebooted my pc. I was able to "press enter to choose operating system" and I choose ubuntu(it was a blue coloured window with two alteatives windows 10/ubuntu). When I pressed ubuntu the screen went black for a couple of seconds before displaying a error saying that the operating system was not able to boot(it said windows even though I choose ubuntu) and it gave me this error message(the text around is in Swedish so I only took a picture of the part that seemed important).Attachment 269744It said that I could press [esc] to get to another menu(I think it was UEFI) , and I tryed that next I pressed the (UEFI) alteative in a list of options and pressed something like dvd>boot>boot(something) and it opened the ubuntu menu(verify files, try without installing, install). The first times I chose try without installing and it loaded for too long before a bugged version of ubuntu appeared(it did not register mouse presses and such). So I shut of my computer by pressing the hardware power button the get the shutdown restart and something else menu and then I could navigate to the shutdown option end press it with my keyboard. The latest time I tried the same steps UEFI and all of that but I pressed install instead, it took a long while but I got a screen with bugged characters, I pressed next and got a even more bugged screen so I tried to stlp the installation and when I tried to do that I managed to get the confirmation window open and it was really bugged so I took a picture of it.Attachment 269745

I´ve got a gtx 750 ti graphics card and I use two monitors(if it matters).

What is happening?
How do I install ubuntu?
How can I fix the error.