Welcome to the site, this is a very good poem, a few grammer mistakes; like capitalize the i's and beginning of every sentence, also put commas and periods in proper place, but this truely is a good poem 5/5!!!
this is what it should look like

To You

To my first and my only,
to my one true desire,
to the one who stole my heart
and the one I'll never retire.

Your the only one I truly care for
and your the only one I truly need,
your loves the only one
I will truly ever keep.

I wish I could explain my heart in two words
and on how you make my love grow,
but until the day my heart can exclaim
I guess you will never know.

you can change it or not, but that is up to you, i think this is a very good poem.