[Not a question] Car plate detecction.

Step 1) Do a little research. Google is a good start point
Step 2) Start coding
Step 3) Compile and use the debug to solve little issues
Step 4) When you get a problem you don't know how to solve but at least you tried it, then come back and ask for something concrete with a snippet of the code giving problems

Sorry if this is not the answer you were looking for. But your question is a bit too wide to be answered at the "Quick" Answers. It is better and you get faster help if you make 10 concrete questions about concrete problems, than a big question about a "how-to guide"