Lightbox for Image in Text Block

I’m putting an image next to text in a text block because I need it to line up correctly and with Avia it won’t get small enough next to the text to look right.

How do I make the image inside the text block have the lightbox feature? I need the image to be 100×100 and then when clicked pop into lightbox with a 900×900 image. I have both resolutions already on the server.