I would just begin to expand on your back-end skills. Since you have HTML/CSS/JQUERY under your belt. Continue to work on those, and also begin with a database

I would just begin to expand on your back-end skills. Since you have HTML/CSS/JQUERY under your belt. Continue to work on those, and also begin with a database (MySQL works fine), once you learn basic database-ing, then begin working on the controlling logic between the two. I would recommend PHP only because it's a quick language to learn and get busy with. This gives you a solid set of skills and a good view of the process. From there you can begin to enhance what you do with the two. Nothing needs to be super-advanced, get down and dirty and learn quickly; more advanced work will come with time. As biscarch said 'just start somewhere'.