The presumption seems to be that you will use the internet, either by transferring them as email attachments or maybe using something up there in the cloud. But you may want to be a bit more private that either of these.
There is a capability of transferring via the USB socket, but the filesystem is an MTP format, not native to anything, so you have to go througn some steps to do this. I decided I didn't want to bother.
I've used ssh (secure shell) at home for years for transferring files, signing onto another computer remotely, and also the related sftp means of uploading files to my site. It took me a while to get the syntax right. Generally speaking I am using my desktop to interact with the tablet, so given that the wifi address of my tablet is 192.168.1.8, I can type
ssh -o Port=2222 email@example.com
to remotely connect to the tablet, and
scp -P 2222 somefile.jpg firstname.lastname@example.org:/sdcard/
to send the picture somefile.jpg to the tablet.
sftp -o Port=2222 email@example.com
sets up an sftp connection to the tablet, where you might serially send and receive a number files to/from the device. For example, after connecting with the sftp command above, I could type
to accomplish the same thing I did with the scp command, but afterward, I'm still connected to the tablet, until I type 'bye'.
would download anotherfile.jpg from the device.
Once I have the file there, then typically I may use File Manager HD to move it where I want to. It's helpful to know which directories your files are in, since some apps have minimal ability to search directories.
SSHDroid is only setting up your tablet to be a receiver from other computers, it's not loading an ssh binary on the tablet.