Learning how to build a sonata can help us writing music in general. By developing a solid perspective on how a classical sonata is built up, we can certainly gain more confidence when organizing our own musical speech.
The Sonata form has been intensively analysed for the last 200 years. It reached its peak during the beginning of the 19th century and since then it has been modified and enhanced.
The exposition is the opening gate into the sonata. It is built up of three functions: Main theme, transition and subordinate theme. This structure can and is certainly varied.
The transition is one of sonata's most characteristic fuction. Juan Rezzuto is publishing some brief articles about how to analyse it. I reccomend you keep an eye on WKMT's blog.