I will explain that a Shakespearean sonnet is written in iambic pentameter (which means 5 repetitions of a weak stress followed by a strong stress-- for example, 'toDAY / i FOUND / a DECK / of CARDS / at HOME').
And the rhyme scheme of a Shakesperean is abab cdcd efef gg. This means that it is composed of 14 lines (of iambic pentameter), that they are grouped into 3 quatrains (abab, cdcd, and efef) plus a closing couplet (gg) and that the ending syllables of each of the lines represented by the doubled letters in the rhyme scheme have the same sound.
So the first quatrain (abab) might be something like this:
Today I found a deck of cards at home,
And looking at their faces gave me pause:
I wondered if I wrote the King a pome,
The Queen would scratch me with her hearty claws.
This is a quatrain of iambic pentameter and the beginning of a Shakespearean sonnet. What you need to do is write 3 quatrains. The 1st line must rhyme with the 3rd and the 2nd line must rhyme with the 4th, but the quatrains don't have to rhyme with each other.
And then you must write the final summing-up: the two rhyming lines of the final couplet:
And so I learned that playing cards is fine,
So long as kings and queens are kept in line!
Oh, and one more point: the whole thing (all 14 lines) should tell a tale and preferably point a moral. Give it a try-- it's a lot of fun!
Post it here, and we'll critique it for you.