Many advantages to the CLI - especially it is easy to script and automate.
What is e:? Are you referring to another computer or your E drive in your windows box? If another computer, what happens when you ping e? Does it resolve to an address?
When scp sees a ':' it believes the part before the ':' is the hostname of another computer.
Here is the command I think you are trying to use
change to the directory in which file is located (not sure how to do that in putty on windows anymore) scp test.txt firstname.lastname@example.org:/home/darius
Note that the @ separates the username from the hostname. Then the : separates the hostname from the directory structure you want to traverse to place the file.
scp from linux command line will copy to an ssh enabled server. If you are tring to copy with SCP from linux to windows, you will probably fail. if you are tring to copy with scp from windows to linux you will surely fail, unless you have cygwin or something similar installed (Dunno if win include an scp utility in their latest versions).
For you the best choice would be winscp.
If you want to do it over linux, it will be a bit more tricky.
Yes, sometimes you need to read some manuals to something you don't know about. Or ask someone. If you don't care to learn about it, just do it the easy way. If you care to learn something, you will have to do some reading/research. Depends on your needs.