Place the .srt file and the video file in the same folder. The name of both files must be exact, except for the format extension.
Open the video using VLC player. It will automatically find the .srt file and show the subtitle. If it doesn't, just drag and drop the .srt file to the video window.
If VLC still doesn't show the subtitle:
Right-click on the video area, select "Subtitle" and then "Add Subtitle File" and browse to the srt file.
Or click on the "Subtitle" menu and then "Add Subtitle File" and browse to the srt file.
If subtitles are hard to read within the video, you can modify the colour or the position of the text. Here are the instructions: