Currently there are many types of finders. Each finder type requires a mount to attach it to your telescope tube.
You have to beable to adjust the finder scope or site so it co-aligns with your main telescope primary viewing direction.
Below you will find finders I have build over the years.
Simple Monocular or Binocular refractor elements can make a simple finder.
The simplest finder is a gun open site bar.
More complex finders use Laser pointers, and bulles eye laser illuminate finders that provide no light gain for the eye.
A good finder should let you see faint objects so that you can point your telescope to within the field of view of the
main eyepiece being used.