Structure: I am wearing trousers and I have a shirt.

Structair: Tha briogais orm agus tha lèine agam.

We already know the structure to say that we have something, but we will recap them very quickly here. 

lèine agam

shirt at me

A bheil

Is

agam?

at me?

A bheil lèine

Is shirt

To ask what someone is wearing, use the phrase  Dè tha ort?

Dè tha ort?
What are you wearing?

This literally translates as ‘What is upon you?’

air + mi orm on me 
air + thu ort on you 
air + e air on him / it 
air + i oirre on her / it 
air + sinn oirnn on us 
air + sibh oirbh on you  
air + iad orra on them 
Dè tha air?
What is he wearing (on him)?
Dè tha oirre?
What is she wearing (on her)?
Dè tha oirbh?
What are you wearing (on you)?

We already know the structure to say that we are wearing something, it is the same as saying if we are suffering from a particular ailment.

VerbNounPrepositionPronoun | Noun (subject)
A bheillèineorm
Nach eillèine-tort
Thabriogaisair
Chan eilsgiortoirre
dreasaoirnn
seacaidairoirbh
còtaorra
adMàiri
fèileadhCalum
lèineEilidh
lèine-tair + domhac
briogaisair + dochèile