A limerick has five lines.
Lines 1, 2, and 5 have seven to ten syllables and rhyme with one another.
Lines 3 and 4 have five to seven syllables and also rhyme with each other.
Here I'll give you an example:
My rhyme is beginning to stink.
They should prob`ly be washed down the sink.
If I could clean`em with soap,
then there`d be a bit more hope,
I`d go back to indullable ink.
Now there are many more rules to Limericks as far as word sounds. Writing a simple standard limerick seems the best choice for beginning limerick writers, such as myself.