How Can I Force Execution to the Catch Block?

Yes, you have to throw exception :

  try
  {
    throw new Exception("hello");
  }
  catch (Exception)
  {

     //run some code here...
  }

   try{
      if (AnyConditionTrue){
              //run some code
               }
      else{
              throw new Exception();
          }
   }
   catch(){

      //run some code here...

   }

But like Yuck has stated, I wouldn't recommend this. You should take a step back at your design and what you're looking to accomplish. There's a better way to do it (i.e. with normal conditional flow, instead of exception handling).

Rather than throwing an Exception in the else, I would recommend extracting the code from your catch into a method and call that from your else

try
{
    if (AnyConditionTrue)
    {
        MethodWhenTrue();
    }
    else
    {
        HandleError();
    }
}
catch(Exception ex)
{
    HandleError();
}

An effective way to throw an Exception and also jump to Catch as so:

try
{
   throw new Exception("Exception Message");
}
catch (Exception e)
{
   // after the throw, you will land here
}