how to back up my file this

[parmardharmesh960140]

i can lost my all documnet how to back i dont have any idea so you can gave me any idea as suggestion so i can bakc to my documents

 

[Saga Lout]

I know nothing about iPhones or iAnything else but this site seems to know it all:-

https://support.apple.com/en-us/HT203977