How do you use the Artemis' arrow on your mare on Howrse?

There are a few ways.

1. Go to your mare's page, under her picture is some boxes, there is a box that has a yellowy-greeny background colour, it's a small rectangular box, you should see some Words in red in the right hand corner of it, click it, choose the A.Arrow.

2. Go to the Black Market, scroll down, you should see a list of what items you have on the right hand side, click the A.Arrow, choose how you will get it (paying a pass or getting it from your inventory. Choose what horse, then click confirm.