You have to weave it in like Ugh said. An example would be

#showtooltip
/castsequence [yourdpstargettingschemehere] judgement X, crusader strike, divine storm,, crusader strike, judgement X,,
/cast [target=tank] flash of light


the extra commas allow the cast to go to the next line of the macro which is your heal spell which targets your tank. if you use focus in your macros you can do [target=focustargettarget] to make sure you always heal the person that is being targetted by the focustarget. if you just use assist you can use [target=targettarget]

Edit: messed up and forgot to mention your other pallies. Just use different comma's in different places to make sure it gets split up amongst your team. if you are a button masher you can add more commas in your dps sequence and/or your healing sequence to find out which works best so that you don't overheal if not needed.