Im sure this is a stupid question, but how do I add a mod to a weapon? I cant seem to select anything from the page to add.

If you are on mobile, the easiest way is to click on the crystal in your inventory and select "modify weapon." Then you click on the mod slot you want, otherwise you go into your armory and select "modify your weapon." Then you can drag and drop the crystal into the slot you want.

Thank you very much,

Good to know. I normally do this on a computer and then go back to my phone.