Fortunately, there is an easy way to convert files that are already in your Google Drive into one of the Google formats, allowing you to edit, collaborate and share. Here's how:
- Select a file in your Google Drive by checking the box to the left of its name
- Click the "More" button that appears at the top of the Drive list
- Select "Open with" from the menu and click "Google Docs" (or Google Sheets or Google Slides)
- After a few moments, the files will be converted into an editable Google Document, Spreadsheet or Presentation
- You will now have two versions of the file in your Drive;
- You will have the original, unconverted file that you can download in its original format
- You will have an editable and shareable Google Document, Spreadsheet or Presentation
You can find more information about converting files to Google Documents, Spreadsheets and Presentations in the official Google Drive Help documentation at https://support.google.com/drive/answer/2407404?hl=en.
If you run into any issues when trying to convert a file, here is some information about the size limits, as well as other limitations, https://support.google.com/drive/answer/37603.