Make your Note field an Auto-Enter text field. Set it as auto-enter by Calculated Value and type the sample calculation below:
If ( IsEmpty ( Self ) ; "" ; Self & ¶ & ¶ & "Noted By: " & Get ( AccountName ) )
This will add the "Noted By: (name of user)" below the value of the Note field. Example, if User1 has entered "This is a sample note." on the Note field, you will see:
This is a sample note.
Noted By: User1
My response here assumes that each note will be recorded in a different related record, not all "mushed together" in a single text field.
You may just want to include a text field that auto-enters the creating user's account name in the same table as the note field.
Color coding is possible, but not exactly simple. You could use conditional formatting to use that account name field to specify different text and/or fill colors for the note field. But that's pretty inflexible, you could easily end up having to modify the layout's conditional formatting each time you add or change users.
But you could also set up a related "user table" with one record for each user with their user name in the field. A container field in each record of this table could have a different color rectangle (this rectangle can be created in layout mode and copied to the clipboard to paste into the field after changing to Browse mode.) for each user. This container field, formatted to "reduce or enlarge to fit" with "maintain proportions" deselected can be placed behind your notes field if you give the notes field a transparent fill color setting to color code each note record for the user that created that note. This make managing your list of users a mostly data entry task in the User table. (but you'll still have to have a means of creating or selecting a color for each user record.)
the note field is only one and everyone write in that field.
jim paul give me a good solution, but if 2 users write in the same row (yes it's possibile) the note field became :
the customer pay 50 € send goods for free - writed by : pc10 - writed by: pc17
who wrote what?
I do not recommend that you use a single field. It's much simpler to use a related table in a portal. Note that the problem you just reported would not exist with a table of related note records.