varchar for loops possible?

I have a table with a varchar column.

I want to select the distinct values from this column and loop through
them (using as a variable) in a raise notice statement and also in an
update statement.

I have not been able to do this trying over 100 things in the last two
hours.  I could not find an example on google.

     for tmp_var in select distinct(value) from mytable where
value2='literal'
     loop
         raise notice 'I want to print a message here - the tmp_var is
[' || tmp_var || ']';
         update table set varcharid = ''' || tmp_var || '''
     end loop;

tmp_var has to be in  ' ' ticks or will not work.  it is failing on the
first FOR statment stating:  "invalid input syntax for integer:
"some_distinct_value".

How do I select varchar distinct values and iterate using variables in a
raise notice statement and inside another update statement?

this seems simple to do , but have not found a way.