I agree that the first thing is to establish what the dinghy is made from, then go online or visit your local chandlery to get the correct adhesive.
However, what you do next depends very much on the extent to which the joints have actually come apart. In my experience, only relatively small tears and damage are straightforward.
I suggest that you Google "repairing inflatable dinghy" - there are several sites which provide good information.
Leith (rhymes with teeth) is the port of the City of Edinburgh in Scotland. A Leither is someone who comes from that area.
I must go down to the sea again, to the lonely sea and the sky - I left my shoes and socks there, I wonder if they're dry?