[stintaril]

Are you referring to front-end design/development? If so, there are many subscription based websites as well as free websites to use.

Sub-based: CodeAcademy (mentioned by anthonycerra), teamtreehouse.com and codeschool.com are a few.

Free: Udacity.com (some HTML5 and design courses), w3schools.com and stackoverflow.

As systemtrigger said using Chrome Dev tools and changing style rules is incredibly useful. Do not neglect using dev tools. In Chrome shift+control+j will bring up the tools, and I highly recommend just playing around in that environment. Type in scripts in the console and just see the different things you can do with JQUERY and Javascript.

Best of all is to have a basis for an idea and just start hacking something together. If you have any questions you can email me at [e-mail] and I will try and help.