Don’t let it intimidate you; it’s just like Legos.
For install: extract files info ’assets/snippets/miniphoto/’ and make snippet ’MiniPhoto’ from ’miniphoto.snippet.php’
So unzip the .zip file, and upload the miniphoto folder to your site’s assets/snippets/ folder.
Delete that snippet.miniphoto.php file (or rename it to snippet.miniphoto.php.txt) from your assets/snippets/miniphoto folder; it’s dangerous to leave non-included .php files laying around like that.
Then in the Manager, go to Elements -> Manage elements, and the Snippets tab. Click on "new snippet". Give it a name, MiniPhoto, and a description if you like, maybe "resizes photos for display". Copy the text from the snippet.miniphoto.php file and paste it into the snippet field.
Now you can use the snippet call in the src attribute for your img tags, and it will resize the image before it gets sent.
<img src="[[MiniPhoto? &file=`assets/images/myimage.jpg` &width=`100` &height=`150`]]" alt="My Image" />
Instructions and a description of the possible snippet parameters are in the beginning of the snippet code.
I just used it in a very simple way in a Ditto chunk tpl, having the image path inserted automatically by a Ditto placeholder from a TV named "photo" used to upload the image
and two parameters to set the width and height.
&width=`100` &height=`150`