Hi here is a small snippet. If you have your access database in your app_data folder and need to add its connection string in the web.config file, so that you can use in your business tier or code behind, here is the snippet.

<connectionStrings>
 <remove name="LocalSqlServer"/>
 <add name="AccessConnectionString" connectionString="Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|AccessDatabase.mdb" providerName="System.Data.OleDb"/>
 </connectionStrings>