Correct! You don't need to install Odoo on the Posbox. You'll install it on a PC or server and you'll install the posbox image on your raspberry Pi

I've installed my raspbian in raspberry pi, whether sd card to install the image posbox can use sd card that I use to install raspbian ? or I should buy a new SD card ? how to connect posbox with the server ?

You should put your Posbox image on an SD card. You can connect the posbox to your Odoo by installing the POS modules in your Odoo (search for pos in your local modules). If you have a ticket printer and can connect it to the Raspberry Pi you can also check the status of your Posbox thanks to the ticket that gets printed.

I already have the sd card that contains raspbian, can I format it and then I fill it with posbox image? do i have to install odoo 8 in pc server? Can I use version 7? sorry too much to ask, because I am a beginner thank you

If you don't need the rapsbian that is installed on the SD card you can just format it and put the posbox image on it. You will need to install Odoo on a pc or server, either way will work. The best is to install it on a Linux server. You can use version 7 but if you can you should use as it has more features, both for POS and other modules.

okay! I will try it. I also use ubuntu linux as the server. Here (https://www.odoo.com/shop/product/point-of-sale-posbox-312) said we could use the android tablet, how do I do it?

You'll need to go a step further for that. You'll have to point your Odoo instance (Linux machine) to an IP or to an URL (http://www.yourdomain.com:8069 for example) and then you can access your Odoo on the Android tablet. From there on everything else will communicate with the PosBox (image) if you've set it up correct. You can read more about this here: https://doc.odoo.com/trunk/hw_proxy/

oh like that? may be too much for me, there is said that we have to connect to the local network posbox. how to connect it ??

It all really depends about what you want to do.. If you want to setup a scale then you will need to connect the scale to your PosBox and then the PosBox should be connected to your network with an ethernet cable. If you also want a ticket printer for example you will need to connect it to the PosBox too. I'd suggest you to create a new question which details what you want to build and then ask all your questions honestly. This'll give you a better overview and understanding!

Okay, thanks for your advice,