Hi
As Flux said I would think your resin is already polyester, the catalyst will be MEKP (Methylethylekeytoneperoxide. incase you are curious) The thing to watch is it has a shelf life and does not like moisture, so do a test batch to prove viability. Add between 2% to 5% catalyst to resin depending on ambient temperature. If you mix it too strong to try to speed things up it will go exothermic, so keep a note of the mix you used for the test batch, if I was using old resin I would try to aim for an 8 hour cure time, but leave it 24. It may also be sticky on the outside but as long as it has gone uniformly hard you can wipe the sticky film off with celulose thinners.
Also polyester will degrade at a lower temperature than other resins recomended on here. I would still read this site a lot more, the information and the possible pitfalls will be on here somewhere.
Hope this helps
Brian.