There are online courses now for Spanish as there are for many languages. If you are a beginner, a good place to start is the BBC Spanish learning website. This is free, and gives you the basics in a clear, fun format. I used this site to get a little basic Spanish for my holiday a couple of years ago, and it worked very well. There is audio and video too, as well as links to help you find a 'live' course near you if you want some face to face practice.
If you put 'spanish lessons online' in a search engine you will find other free sites too, so try some of these before you look for a class.
Once you have the basics you could try some lessons online. These are usually via Skype, mostly with a webcam though not all classes use them. These classes are quite good because you can share a screen with a teacher who can write down new words, give you written exercises etc - it's not just conversation. You could go for a virtual school like this one or just look on a networking site like gumtree for a private tutor - generally, online lessons shouldn't cost too much.