Here is a guide on how to upgrade from whatever OS you are running to windows 10.
1. you need to download the ISO after registering to the insider program.
http://windows.microsoft.com/en-us/windows/preview-iso
2. After downloading the ISO, you need to open it up [With windows or another archiving program] and put the contents of it on some type of removable media that has over 4 GB of storage. EX: Sd card, USB drive [if installing on non-uefi pc, the boot sector must be created on the usb drive], DVD [reccomened to use the os's built-in capability to burn iso to dvd].
Only do this step if you are running windows: 3. You should be able to run the installer on the removable media and follow the instructions on screen! Your computer should restart, which is normal.
Only do this step if you are not running windows or have problems with step 3:+ 4. Turn off/restart your computer. On the splash screen, there should be a button to enter boot menu or setup. Hit that button and make sure to boot to the flash drive. After that Follow the on screen instructions. It should be pretty similar to the windows 8 installer.
5. Remember to install the drivers for your system available from your motherboards' or gpus' manufacturer's website, also https://ninite.com/is a good website for installing software quickly.
6. For a shortcut on installing drivers [Only works with some of them] Make sure you have a working internet connection, and press windows + x, then hit device manager. There should be some uninstalled drivers marked with a Yellow triangle. Right click those drivers and then hit "update driver software". At least some of your drivers should install successfully this way [Your display driver always should].
Thats it! You should now have windows 10! If you have any suggestions/corrections/things i should add, make sure to leave a comment.
Edit: partial credit to @Speedbird for some additions