There are varying degrees of rules, some easier to master at first. I'll teach you what I learned. There are other ways.
Here is a normal English sentence:
I want to go to the store.
Here is the same sentence, but rendered in Pig Latin:
I-yay ant-way o-tay o-gay o-tay e-thay ore-stay.
To form each word, take the initial consonant (or consonant cluster) sound, suffix it to the end, and add an 'ay' sound (like the 'ay' in say - in Spanish, 'ei'). When the word doesn't begin with a consonant sound, only the 'ay' sound is suffixed. However, some people like to throw in a consonant to make up for the absence of one. So, you'll also see -way, -yay or -hay as a suffix. I learned to use -yay.
Here are some more examples:
through -> ough-thray
feast -> east-fay
sorry -> orry-say
quiet -> iet-quay
eagle -> eagle-way (eagle-yay, eagle-ay)
You can try out this
Pig Latin Translator site.
(There's a box to check under the translation area if you want to see the hyphen.
I think some sort of punctuation is needed. Otherwise, 'ayspray' could be translated back into English as spray (ay-spray) or prays (ays-pray).)
Some people like to split compound words into respective parts.
For example:
international -> inter-way-ational-nay
multilingual -> ulti-may-ingual-lay
bedroom -> ed-bay-oom-ray
buttermilk -> utter-bay-ilk-may