how can i open whole forum if i dont have buyed domain and hosting ?
i mean can i some how run the forum just into my com ?
I'm not quit sure what you want:
1) There are a couple of free hosts where you can create a free smf forum. If you do a search in the hosts & hosting board I'm pretty sure you'll find some.
2) You want to run SMF on your own computer. You can do that, but I don't recommend it. You'll probably get a lot of problems if you don't have any experience in configuring & managing servers.