Can I force Mac OS X to select certain Wifi network?
Sure. Just go to System Preferences/Network, select Wifi and click Advanced. A list with all the Wifi networks you've been connected to will appear. Just rearrange the connection order (the ones you'd like to connect first on top) by drag-dropping. 

Also, delete any unwanted network SSID (network names) if you no longer want to auto-join that.