Como deixar forma atrás do texto ?

Jorge,

Edited, now as an extended instruction with the addition of step 0).

For outlined Type you can do it with an Offset Path with a positive offset sufficient to close all the gaps followed by a negative offset to reach the desired final offset. You may need a few attempts to get it right, so Undo is your friend.

You can do it as follows:

0) With the text created and outlined, Ungroup and turn all the (Compound) Paths into one single Compound Path;

1) Copy the text Compound Path behind itself and change the colour of the copy to a preliminary colour, then apply Object>Path>Offset Path with a positive offset sufficient to close all the gaps; you may need to try a few times until you succeed in closing all the gaps without overdoing it;

2) Apply Object>Path>Offset Path again with a negative offset to reach the desired final offset, and change the colour to the desired background colour to be able to see the resulting shape;

Delete the path with the preliminary colour.

The negative offset is simply the difference between the desired offset (width of the band where it is closest to the letters) and the offset needed to close all the gaps.

In some cases, depending on the typeface and distances between the letters, you can also do it with live Type, probably possible in the case shown.

@Jorge Gossain Neto trying to figure what exactly you are trying to accomplish here. Are you trying to do this:

or is there a reference of an image that you want to replicate?