Most suppliers of refill kits will give a full instruction leaflet on how to do the refill.
I stopped doing refills years ago as it was very messy. I now only use compatible cartridges from Choice Stationery for my Epson printers, but I think where ever you go for ink for a lexmark you will be paying the earth. Do you know what the cartridge numbers are for the 1180? If so you could try looking here: click here or click here for cheaper compatible cartridges.