We assume that the MS Access database in located in the /database folder outside of your web root directory, which is recommended for security reasons.
string databaseName = "YourDatabaseName.mdb"
string pathDB = Server.MapPath("/") + @"..\database\" + databaseName;
string strConnection = "Provider=Microsoft.Jet.OleDb.4.0;";
strConnection += @"Data Source=" + pathDB;
objConnection = new OleDbConnection(strConnection);
DSN-less connections are faster and more reliable.
These examples may not work for you without certain modifications.
The purpose of the examples is to give you a general idea on the topic.