To edit files with pico, you do the following.
As with most *nix software, you type the name of the file you want to send to the software,m after the name of the program.
EG, in the eggdrop directory, type
pick MOTD
Move about the file, and make the changes required.
To save the file, hold the CTRL button, and hit x, it will then ask if you want to save changes, so hit y to confirm this. Then hit return again to confirm the name of the file you wish to save it as.
Pico will now exit, and the file will have been saved.
Other methods are to download the MOTD file, edit on your own system and then re-upload the file, back tot he shell.