English Sonnet

1. It must be 14 lines (instead of sentences, poems are written in lines, so you stop on each line, and count down 14) 

These are grouped as follows: 3 quatrains and a couplet.
What does that mean? 3 sets of 4 lines (think a quarter) and a couplet (2, like a couple).
So your laid out poem should look like: 4 lines, a space, 4 lines, a space, 4 lines, a space, 2 lines. 

2. Each LINE must only be 10 syllables long (though this is only the “pentameter” part of iambic pentameter, it is better than nothing! it would be far too difficult to do full iambic pentameter!).

How do you measure that? try tapping or clapping to measure your syllables (like flo-wer : 2 syllables,  ba-by : 2 syllables, de-so-late: 3 syllables an the like) 

3. Last requirement! And this will look like the hardest, but it isn’t once you get past the letters. You have to follow the Shakespearean Sonnet Rhyme Scheme. It looks like: abab cdcd efef gg.

I know, WHAT?? but, think back to the requirement 1, where I told you how the poem has to be laid out, in 3 quatrains and a couplet, so 3 sets of 4, and a couplet.
Now look back at this rhyme scheme abab cdcd efef gg.
Notice it has the same number of letters and in the same spacing as what I told you your poem should look like? abab (quatrain, which is a set of four lines) cdcd (quatrain) efef (quatrain) gg (couplet).
All this group of letters is telling you is what lines in your grouping of lines should rhyme with each other. 
SO in quatrain one: abab, lines 1 and 3, and lines 2 and 4 rhyme.
In other words, throughout the poem, every other line rhymes, but does not have to rhyme beyond its own quatrain, if it did it would have said abab abab abab, but it doesn’t, the rhyme scheme changed in the next quatrain, abab cdcd efef gg, letting you know that as you go into your second quatrain you can change your rhymes (rhymes are the last words in the lines). and finally the couplet at the end (gg) two lines that only rhyme with each other.