Try this tool by Cruicial by typing in which model etc of Pc you have.
HERE This should tell you how many slots your PC has and will tell you exactly what kind of memory you need. Write ALL the information down that it gives you.
I would buy memory from EBuyer
HEREYour PC should have come with some kind of paperwork. Basically you are looking how to open the side of your machine, turned off obviously
This guidse, with pictures should give you an idea of what and how to do it step by step
HEREYou should see the memory slots as you will see your current memory card in there. Have a look to see how the 1st memory card is slotted in and then push the new one in the 2nd slot. clip it in with the clips. Put the side back on, reboot your PC and hopefully your PC should auotmatically recognise the new memory.
It may sound or look complicated but I swear it isn't and a machine like your could take at least 1gb of memory
Also if you've got a built in graphics card this will be using up some of your 192mb of memory too.