This may seem excessive, but when I think of the wasted time I have spent trying to find a demonstration of how I embed a figure in an html doc, I cringe. This is a script that takes an image file and a text file (the start of a caption) and generates the html code you need. I usually just redirect this (from standard out) to a file and then read it into my destination html doc.

% ls
drift_test1_bsc5-5612.png  simple.text 

% cat simple.text
This is a simple caption file that tells me 
something interesting about my figure. 

% build_htm_img drift_test1_bsc5-5612.png simple.text >TTT 

This is a simple caption file that tells me something interesting about my figure.