BindEmployeeData is missing the final closing curly bracket:
public void BindEmployeeData()
{
try
{
...
}
catch (Exception ex)
{
...
}
finally
{
...
}
protected void btnAddEmployee_Click(object sender, EventArgs e)
{
which means that it assumes btnAddEmployee_Click is a part of the function, and no access modifier is legal there.
Fix that, then reindent your code (VS will do it for you if the brackets are all correct) with "CTRL+K D" and that should fix it. If VS won't, then the brackets aren't correct, so start by looking at where the first error occurs and check the method above that.
Since you code isn't complete, the first fault is the only one we can find for you - you need to get used to looking for these problems yourself, as you will see a lot more of them in the future (we all do), and it's a whole load quicker to be able to spot them yourself instead of waiting for others to do it for you!