In order to be able to mount a share within an NX session, you will need to have a share exported on your client machine. This means, for example, that on a Linux  machine you need to have a Samba server and on a Windows machine you need to have a shared folder.

At that point, it will be up to NX node to mount the share on the remote machine as a smbfs or a cifs share.

Since the Solaris kernel doesn't support either smbfs or cifs, NX is at present unable to support samba shares on that Operating System running NX client.

However, if NX Node is running on Solaris, you should be able to browse and manipulate shares using the user-land tools in Solaris (smbclient or smbsh).  Of course this is true only if the share machines are connected to the LAN and there is no software preventing this from occurring (firewalling software, iptables etc.) 

More information about how printer and file sharing work in NX 3.5.0 can be found at: https://www.nomachine.com/AR08D00413