Left-Click on the friend button or press [O] on your keyboard, then select the foes table.
You will see numbers arranged from 1 to 64 on the right hand side of the screen that represents your current foes and the maximum amount of foes that you can have in the right-hand corner of the foe interface.
You can’t add foes manually, these players will automatically be added to your foes list once you are killed by them.
Foe Enquiry allows you to find the location of an enemy player by right-clicking on the foe that you would like to locate and selecting the foe enquiry option. However, this foe of yours must be online.
This function will consume an enemy inquiry scroll which can be obtained as a daily sign-in reward, or by purchasing it from the prepaid market.