hexchar des?

hello
im a new here, i read wiki pages. some topics here on board but im still little confused

okey,lets start with questions

i make an example, des encryption
key
0123456789ABCDEF

data to encrypt(decrypted data)
00000000FFFFFFFF

encrypted data
7A3DD240054567CB

i have 2-3 question about it
lets say that i know from encrypted data 2,3,4 byte, i create cmd but im not sure thats corect


and after that cmd i get error like "line-lenght exception"
is that cmd okey ?
maybe txt file with encrypted data is wrong format? (i just put clear encrypted data)

and another question, there is a way to see also the "key" ?

many thanks guys for help's