TUTO de softpedia en anglais , pour installer le dualboot entre windows 10 et ubuntu : (je ferais un tuto francais quand je ferais mon installation)
So the first thing you want to do before attempting to install Ubuntu or any other Linux OS alongside Windows 10 is to enter your computer’s BIOS/UEFI and disable the Secure Boot option (read the manual if you do not know where it is because there are different types of BIOSes). Make sure you read the update at the end of the article on the Secure Boot matter.
Partitioning your Windows 10 disk drive
Before installing Ubuntu, you need to partition the Windows 10 disk drive. There are two scenarios at this point, but first heck to see if you have a single partition dedicated to Windows 10 or multiple ones. In the first scenario you have a single partition that you need to shrink, but make sure you have enough free space to do that.
In the second scenario, you have two or multiple partitions, and you need to decide which one to erase for your new Ubuntu OS. In both cases, right-click on the Windows Start Menu, and choose the « Disk Management » entry from the context menu. In the first scenario, right-click on the (C:) drive and select the « Shrink Volume » option.
Set the size of the new partition for Ubuntu, which depends on how big the disk drive is and how much free space is available, so it is your decision, but keep in mind that you need at least 10GB for the installation of Ubuntu (20GB is recommended). Now close the Disk Management application and continue with the guide.