If you are in the country where you can find monk in (Theravada), food offering, any donation to the temple are the ways. If not, you can donate money or belongings to person in need. It is not difficult to find any charity organization in your area or even search on the web the organization that you like best.
There is no official ritual in offerings to dead relatives, though there is some pali phrase about that. But it is not about the saying in language that you even don't understand to complete the process. It's about your intention.
Words that you can say or think (recite in your thought) before, during, and after such donations can be in the following way: With the good deeds I have done, I would like to consign merit to ..................... (your relatives' name). May he/she acknowledge and rejoice the good deed that I have already done.
ฺBasically, every good deeds, act can be consigned to the dead. The donation seems to be the most convenience one. There are what we called 10 bases of meritorious action, if you have done any of them, you can consign to your relatives and other who had passed away.
bases of meritorious action)
1. meritorious action consisting in generosity; merit acquired by giving
2. by observing the precepts or moral behavior
3. by mental development
4. by humility or reverence
5. by rendering services
6. by sharing or giving out merit
7. by rejoicing in others’ merit
8. by listening to the Doctrine or right teaching
9. by teaching the Doctrine or showing truth
10. by straightening one’s views or forming correct viewshttp://84000.org/tipitaka/dic/d_item.php?i=89