How to add Marvel's Agents of S.H.I.E.L.D. s3e21 SRT File:
1. ADD SUBTITLE FILE IN VLC PLAYER:
Browse the tv series file and right click on it.
You will find option of Select Subtitles.
Choose that option than click on Add Subtitles.
Choose the SRT file and your subtitles are added automatically.
2. ADD SUBTITLE FILE IN WINDOWS MEDIA PLAYER OR OTHER PLAYERS:
After downloading the zip file, you need to unzip it first using WinRAR, then copy it to the same folder where the tv series is saved.
For example, if you have a folder name Marvel's Agents of S.H.I.E.L.D. s3e21. Then both tv series and subtitle file should be pasted in the same folder.
After performing the above steps, subtitles will be added automatically.