Adding a smaller subtitle under a title on simple grid portfolio

Hello, I want to add a small subtitles under a title on my simple grid portfolio page.

I tried several CSS that I found on other threads, some worked in grid overlay layout but not in simple grid layout. 

If there's a way to do that please teach me how.

Thanks in advance!

Never mind I figured it out! If there's anyone struggling with the same issue please let me know!

9 hours ago, tuanphan said:

You can use #2 in this thread

 

Thank you @tuanphan, yes I used the one you suggested and it worked! I really appreciate it!