Here's a list of websites where you can tap into the Unity development community to find answers and to ask questions. Please remember to be courteous and respectful of more experienced developers' time. As with any online forum, be sure to search existing content for an answer before you ask a question.
Unity Manual: When you're new to a technology and you ask naive or poorly researched questions, you may hear "RTFM" a lot, which stands for "would you please be so kind as to review the product manual?" Well, here's the link to the product manual, which covers both beginner and advanced topics, including examples on writing your own custom Shaders: