It is possible and how ? title will be a text box, possibly custom with css ?

if I understand you, say you have two columns and one post above the columns

post 1 post 1 post 1 post 1 post 1
post 1 post 1 post 1 post 1 post 1
post 1 post 1 post 1 post 1 post 1
post 2 post 2 ----- post 3 post 3
post 2 post 2 ----- post 3 post 3
post 2 post 2 ----- post 3 post 3
post 2 post 2 ----- post 3 post 3

you want to do something like this

post 1 post 1 post 1 post 1 post 1
post 1 post 1 post 1 post 1 post 1
post 1 post 1 post 1 post 1 post 1
* some more lines of text here *
post 2 post 2 ----- post 3 post 3
post 2 post 2 ----- post 3 post 3
post 2 post 2 ----- post 3 post 3
post 2 post 2 ----- post 3 post 3

you would have to edit the template to do this

Yes it's exactly what i want ... except i have 3 colums above the "post 1", but i don't think that change anything..
I do not think it's possible to add a new widget area to this place, so do you think change the theme to be difficult to achieve this ?

like I said you will have to play with the template and see what you can come up i. Make a copy of template and call it something else so you have the original to fall back on.