How about showing us an example of what you're thinking? At least show us the inputs and the desired output.
The for loop syntax is quite simple:
for variable in word word word; do
The list of words is read after parameter expansion, so if you have variables containing words, or any other kind of substitution, then their contents will simply become part of the list.
var1='a b c'
var2='d e f'
echo 'foo bar baz' > file.txt
for var in $var1 "$var2" $( cat file.txt ) ; do
Notice how quoting affects the result. The contents of a quoted variable will be seen as a single element, while an unquoted one will be word-split before the loop read it.