1. connection with internet and ssh on Guest machine
Firstly u have to install VBoxGuestAdditions and secondly add two adapters ( NAT, Host Only Adapter) and configure it on Debian in /etc/network/interfaces for eg.
2. most complicated was shared folder (/user/Sites) on guest machine. This problem is denied permission to write in directories and files, the solution is easy.
mount -t vboxsf -o uid=0,gid=0,rw,fmode=777,dmode=777 Sites /var/www