Something like this (not tested)

lcNewString=''
#define crlf chr(13)+chr(10)
For lnX = 1 to memlines(lcString)
   lcNewString =Upper(Left(mline(lcString,lnX),1)) + substr(mline(lcString,lnX),2)  + crlf
Endfor
lcNewString = left(lcNewString, len(lcNewString-2))

>Hi
>
>I stored a text into a variable and need to treat it in order to turn capital the first letter of every line.
>
>eg:
>
>acccccacacacacaccacca
>
>dddjjdjjdjjdjjdjjd
>
>xxxxx ddddddd aaaaaaa
>
>annannannannanan
>
>
>Must become:
>
>Acccccacacacacaccacca
>
>Dddjjdjjdjjdjjdjjd
>
>Xxxxx ddddddd aaaaaaa
>
>Annannannannanan