If you want to transfer files from your Windows workstation to your home directory on the cluster you need an SFTP client. A popular option is Putty's PSFTP client. You don't need administrator rights to run this program. You can download the latest PSFTP from Alternative binary files > psftp.exe, then just double click on the file to start the client.

To connect to the cluster run open gateway.hpc.tu-berlin.de

You can move files from your local directory to the remote directory and vice versa. Use lcd to change your local directory (e.g. lcd C:\Users\Username\Desktop) cd to change the remote directory, ls to list the contents of the remote directory you are currently in. Use get -r <dir> to transfer a remote directory <dir> to you local directory and put -r <dir> to transfer a local directory <dir> to the remote directory.

run help to list all commands.

An alternative to Puttys SFTP client is the WinSCP client. It can be installed in inside the users directory, so no administrator permissions are required. A portable version also exists. WinSCP can be downloaded here.
To connect to the cluster start WinSCP and enter gateway.hpc.tu-berlin.de as hostname. File protocol is SFTP port is 22. Then login. Enter your TU-username and your password when asked.