installing mojave will delete my files ?

hi ive a question about the process of installing mojave in my mac, currently i have os sierra 10.12.6 and i would like to install mojave, but im afraid i could lose my pics and files, and right now (this week) i could not make a back up, do you know or have any personal experiences about losing files during an installation process ?(sierra to high siera, or high sierra to mojave)

and what would you suggest me to do?? thanks in advance :)