I am new to shooting a bow. I just bought my first one Monday night. It is a Quest Torrent. I was shooting last night, and I am grouping my shots 1-1/2" low at 20 yards. Should I be moving my pin up or down? I would think I need to move it down to bring the shot up right? Thanks for the help.

Yes, move your pin in the direction that the arrow hit, in your case down.
How much should you move the pin?
Simple method:

Aim at center of the target, shoot your group
Now aim at the center of the target and reference how far you need to move the pin to center the pin over the group. Use the width of the pin, fiber optic or distance to adjacent pin as a reference.

Geometric method:

(distance arrow off(in))  * (distance from peep to pin(in))
–––––––––––––––––––––––––––––––––––––––––––––– =   Distance to move pin(in) in direction of arrow.
(distance shot (yds)) * 36 (in/yd)

The above is in decimal inches. If you want to convert to 16th,32nd or 64th multiply by that number

Example using a 22.5" peep to pin, 1.5" @ 20 yds.

1.5 * 22.5 / 20 /36 = .046875" move the pin, multiply x 32  and you get 1.5 32nd.

(I picked my example peep-pin distance so that I would get 1/32" pin adjustment = 1"@20 yds, you need to use the distance you measure on your bow.)

You can figure your bow's 1/32" pin adjustment = 1"@X yds
(peep to pin) * 32 /36 = X yds

Sample peep distance for 1/32" pin adjustment = 1"@X yds
18"peep 1/32" pin adjustment = 1"@16 yds
22.5" peep  1/32" pin adjustment = 1"@ 20yds
27"peep 1/32" pin adjustment = 1"@24 yds
This is why it is important to draw a consistent distance because it changes your sight profile.

Once you find the above distance for a 1/32 adjustment, you can use the info for yardage adjustment when zeroing differed yardages.
If you are setting a 40yd pin and are 6" low, with a 22.5" peep, the adjustment in 32nds is 6*20/40 or 3/32nd.

The above is for zeroing yardage pins, not for predicting arrow drop at different yardages.

Thanks for the reply!

follow the arrow to adjust your sights, if the bow shoots high move your pins up, if it shoots left move pins left, ect..

Make sure the centershot on your rest is set correctly also! You will be fighting an up hill battle if centershot is off. To check your centershot...shoot a group at 3-4 distances and note the location of each group at each distance. This example will be 10, 20 and 30 yards with you aiming at the bullseye. An X denotes a group...

So...if your groups go like this...

x (10 yards)

  x (20 yards)

     x (30 yards)

You need to move your rest to the left.

If groups go like this...

     x (10 yards)
 
   x (20 yards)
 
 x (30 yards)

You need to move your rest to the right. After getting that straight, then start to sight in with your bowsight.

ETA: This of course will not help with elevation which seems to be  your issue! This may be something to keep in mind however!

Pins are easy.  Just move in the direction the arrow hit, like said.

When you're tuning a rest and/or yoke/cable tuning, then all hardfast rules go out the window.