File sharing is a feature you need to activate in the GUEST / HOST OS'es.
As your Guest is an UBUNTU system you'll need to enable File sharing with Windows using SAMBA to share LINUX with Windows - while fairly simple to set up is beyond the scope of this post here and a simple Mount command for the Windows files to be shared with Linux
First of course ensure that your VM Networking is enabled - Bridged if you want separate addresses for the Guest or NAT if you want to share an IP with the guest.
Next ensure the two machines (Guest and Host) can ping each other
Now mount the Windows file systems you need to access on your Ubuntu guest (READ WRITE option is -o rw) with a "bog standard" mount command -- the ntfs file system must be defined as -t ntfs-3g (no space between ntfs and 3g) in the Linux mount command. mount -t ntfs-3g -o rw /your device / yoursharename
-- Ntfs is supported in Linux kernels these days directly both for Read and WRITE.
To access the Linux file system in Windows you need to set SAMBA up on the Linux vm -- this uses the NFS file sharing protocol. The Official Samba 3.2.x HOWTO and Reference Guide