Usually remotes are kit dependent...
Steelmate kit will work with steelmate remote. ...
If u can access kit just get info of make and model
Get remote and put kit in pairing mode by identifying pairing button (usually like a router reset button you may need ballpoint to press the button some kits need to open top cover to access pairing button )usually 2 remotes can be paired ...
Most easy is to visit shops which install such system they will pair remote for 100 or 200 + remote cost or even do it for free ....
I have no idea about karachi but in rawalpindi saddar babu mohalla is famous for security systems