insert word in each line of a file

can someone tell me how can I insert a word in front of each line in a file.
i tried with sed but didn't managed yet.
Is there another command or this one(sed) works?
10x anyway.

what have you tried exactly?

i've tried
sed i \ txtinsert filename

sed 's/^/newBeginning/' filename

could u pls expain to me what means the expr 's/^/newBeginning/' ?

doing 'man sed' yields:

s/regular expression/replacement/flags
     ____________________________________________________________
                  Substitute   the   replacement   string    for
                  instances  of  the  regular  expression in the
                  pattern  space.   Any  character  other   than
                  backslash  or newline can be used instead of a
                  slash to delimit the RE and  the  replacement.
                  Within the RE and the replacement, the RE del-
                  imiter itself can be used as a literal charac-
                  ter if it is preceded by a backslash.
     ____________________________________________________________
                  An ampersand (&) appearing in the  replacement
                  will  be  replaced  by the string matching the
                  RE.  The special meaning of & in this  context
                  can   be   suppressed   by   preceding  it  by
                  backslash.  The characters \n, where  n  is  a
                  digit, will be replaced by the text matched by
                  the  corresponding  backreference  expression.
                  For each backslash (\) encountered in scanning
                  replacement from beginning to end, the follow-
                  ing  character  loses  its special meaning (if
                  any).  It is unspecified what special  meaning
                  is  given  to any character other than &, \ or
                  digits.

s/^/newBeginning/

's' - substitute
'^' - beginning of the line

10x a lot for help

an awk solution