how to dowloan file to i phone 6 ios 11..

In order to sync files from your computer to your phone, you need to send them to an app that will support that type of file. For example, if you have a word file, you need to sync it to the pages app. Or, as you noted, sync it to an iCloud service such as google drive, dropbox, ect. Once there, you can then access it on your phone. For my documents, I use DocsToGo which lets me sync word documents and spreadsheet documents from my computer to my phone and iPad.

What do you mean by ‘using files’? Please explain what you need to do for us to help you. I do not understand what you want to do.