Need some help installing mods.

So I've started playing aoe3 a bit again... I'm more of a fan of aoe2 to be honest but do like a bit of a change every now and then.

I'm wanting to dabble in modding the game but I literally have no idea how really.... can someone a. Suggest some mods (nothing crazy just advanced features, new civs etc) and b. Explain to me like I'm a dummy how to mod (never done so before and I'm no savant).

Thanks in advance :)