adding hover overlay HELP!

Hello helpful people, I'm looking to add a 'dimming' overlay to an image when the curser hovers over it, my research tells me  I'll need to use CSS code; A. I am not overly confident with code but I'ts something I think I can handle B. It seems fluid engine has made things harder to do in that department.

If you've got this far I am also having trouble with text over an image it always to seems to mess up the image behind it, and you ca't seem to just select a font size it's just presets which is frustrating.

I look forward to hear from you with you're help (I hope😂)

A: yes you need CSS
B: no fluid engine doesn't make it an more difficult

You need to use CSS like this:

#block-yui_3_17_2_1_1669460549609_145289:hover img {
  filter: brightness(85%);
  -webkit-filter: brightness(85%);
  -moz-filter: brightness(85%);
}

But remember to change the block ID to one from your website.