Step 1. Backup the old wallet so you will have a backed up .dat file
Where is that option in wallet? i have only "make a copy of the wallet" is that it?
Is it possible to lose all coins if i do something wrong?
Here is what I do (in Windows):
-stop the wallet
-open file explorer and goto "%appdata%" (this assumes you let it install in the default path when first run)
-copy the "raven" directory someplace (to save space, you only need the wallet.dat file in there, the rest is re-generated when you start the wallet)
-double check what you copied matches what was in the source directory.
I also make sure to run the wallet on a second computer at all times. So take this "raven" directory (you really only need the wallet.dat file since the other stuff will soak up a lot of space) and place it in the %appdata% location. Then put the raven-qt file on your desktop and start it. It will then begin loading the block files in your new %appdata%\raven directory and your coins balance will eventually appear when enough of the blockchain is read in.
I instaled new wallet on new pc, copy wallet.dat from old pc and that's it?i see my coins.