何时使用以及何时不使用Try Catch Finally

I am creating asp.net web apps in .net 3.5 and I wanted to know when to use and when not to use Try Catch Finally blocks? In particular, a majority of my try catch's are wrapped around executing stored procs and populating textfields or gridviews? Would you use Try Catch I am creating asp.net web apps in .net 3.5 and