I am trying to install this mod on the 1.7 version, how do I add ores? I am playing on a modded server.

There is a button in game which you can change in the controls settings of MC. Also, don’t use the mod on a public modded server.

Sorry, it's a friends server and we are lazy but I cannot find the button you are talking about sorry. Could you give some more direction?

I just tried to add an ore from the ore menu and it said it was not supported, am I screwed?

Hmm, I’m not sure what you mean by unsupported

1.7 is extremely old, I recommend you update

I tried updating, but would the newer version still work for 1.7.10 mc.
Also I go to the ore menu and, for example, I put oreMithril. It pops up saying I cannot add ores or smthn like that.

Sounds like you're adding it incorrectly

for example, if you have to type the ore which I think you do in 1.7.10 then you likely have to type the ResourceName so for diamonds, it would be minecraft:diamond_ore

I’ll test it out, thank you for helping so much. I’ll let you know how it goes.

No dice, minecraft:diamond_ore contains data other than numbers and underscores and doesn’t work.

Oh, then it's worse. it wants the ID of the block so for diamond ore it would be 56

So I would just type 56?

Yes

I tried it, it just keeps crashing The game crashed whilst updating screen events
Error: java.lang.ArrayIndexOutOfBoundsException: 1
Exit Code: -1

Sorry but I don't have the time to support a 6 year old version of the game and this mod. Please update to a newer version of forge or post a real crash log. If you can't update for what ever reason, delete the xray config and try again. I can't help any more.