Update docs/intro/tutorial03.txt

docs/intro/tutorial03.txt

@@ -48,6 +48,9 @@ The first step of writing views is to design your URL structure. You do this by
 creating a Python module, called a URLconf. URLconfs are how Django associates
 a given URL with given Python code.
 
+第一步是设计URL结构。首先创建Python模块，并命名为URLconf。Django通过URLconf连接
+和给定的URL和Python代码。
+
 When a user requests a Django-powered page, the system looks at the
 :setting:`ROOT_URLCONF` setting, which contains a string in Python dotted
 syntax. Django loads that module and looks for a module-level variable called
@@ -59,6 +62,15 @@ Django starts at the first regular expression and makes its way down the list,
 comparing the requested URL against each regular expression until it finds one
 that matches.
 
+当用户获取一个Django页面，系统会查询 :setting:`ROOT_URLCONF`环境。`ROOT_URLCONF`含有
+Python语法中的字符串。Django载入指定模版并定位名为``urlpatterns``的变量。
+``urlpatterns``格式如下::
+
+    (regular expression, Python callback function [, optional dictionary])
+
+Django从第一个表达式开始读取整个list，比较requested URL和list中的每个表达式，
+直到找到符合的配对。
+
 When it finds a match, Django calls the Python callback function, with an
 :class:`~django.http.HttpRequest` object as the first argument, any "captured"
 values from the regular expression as keyword arguments, and, optionally,