To edit the content of a file follow those steps:

1- type the vim command + the name of the file you want to edit

Example: vim my_file.txt

2- press the i buttum on your keyboard to be in insert mode

3- Edit or make your changes in the file

4- Press esc on your keyboard to come bac in command line mode

5- Type colum (:) + wq ( w to save your changes and q to quit)