Try downloading your preferred distro/OS (operating system...linux mint...ubuntu...whatever...).....then 'burn' the download to a USB Stick (8 gb is plenty...even 4 GB will work)....using rufus or unetbootin....there are quite a few 'burn' programs out there.....they are 'special' programs that ensure that what you put on the usb stick is bootable
Then....change the boot order on your pc/laptop and boot the usb stick. (the os/distro does NOT install itself to your hard drive at this time. It runs quite happily(a bit slowly) in ram)...No damage can be done.
Thats it...use it and enjoy playing with it....if you screw it up...just reboot to the usb stck again....and play with it some more.
When....and only WHEN...you get used to it and have made the decision to INSTALL it.....(remember installing it will WIPE EVERYTHING on your hard drive)....click the install Icon on the desktop.
It does not really matter if you do something wrong......relax. Just reboot to the usb stick and away you go again. All you will lose is a little time
Oh....and btw...Welcome to Linux.org.......the friendly place !