Mounting a Samba Share on the Raspberry Pi

Install the following packages:

apt-get install  samba-common smbclient samba-common-bin smbclient  cifs-utils

Create a local directory:

mkdir /mnt/abc

Mount the Samba share using your username:

mount -t cifs //server/share /mnt/abc -o user=uwe

If the Samba share is provided by a FritzBox via its NAS feature and assuming the share is named "MyNAS" on your FritzBox, then the above command would be:

mount -t cifs //<FritzBox IP>/MyNAS /mnt/abc -o user=uwe

Based on this SO answer.

Update: if you want the share to be mounted on every reboot, follow this guide (in German).