[penguin_gab]

Learn about HTML5, CSS3 and a little bit of Javascript, enough to understand and utilize jQuery like what bartonfink said. This is as front-end as front-end gets for web development.

Do not worry about design or templating, knowing a bit of Photoshop/ Illustrator is good, but it should not be your priority considering you can buy high quality templates from ThemeForest.net for $10 - $30, or even hire a designer if your budget allows.

Also, you may want to consider working with a web framework to make your life easier, like Django or Flask.

This is from someone who comes from a similar background as you. My background was in C, C++ and Objective-C, and I do mainly embedded systems and low level programming. It took me a few weeks to learn HTML/CSS/JS and another few more to get comfortable with Ruby on Rails, and 1 year later now, I can basically build and prototype any web application I can think of.