Does anyone know how to write a sonnet? i need to write a sonnet about romeo & juliet to show i understood the play.

Depends on the sonnet
Shakespearen is the easiest, the requirements are:
14 lines
iambic pentameter(10 beats per line)
abab cdcd efef gg rhyme scheme
gg is like a shift from the rest of the poem between lines 13 and 14
has to be about some type of love
petrarchan:
14 lines
two stanzas then the two lines
iambic pentameter
also has specific rhyme scheme
Abba Abba cdecde or cdcdcd shift after the first 8 lines
has to be about some type of love
there is also spencerian and modern but these are more common and the shakespeare one is the easier one honestly