I must say, it's refreshing to know that there are some people writing for beginners.
This is a very nice piece, elegant, charming. It very much suits the level of player you are writing for. The melody is simple, catchy. The chord progressions are likewise. Everything technically seems to be in order...
HOWEVER...To sum it all up in one word and a conjuction, it's boring. Like Nico said, you never stray from the tonic key, you use only 1 4 5 progressions for your chord structure, and all in all the piece is a bit "amateurish."
Don't take that too harshly though! You have good musical ideas, but you must vary your theme (as 327o said), suprise the listener and keep them interested, and most of all, you must make your music your own. This piece could have been writen by thousands of people, none of which anyone knows the name of, and would likely, if written 300 years ago be labeled "Traditional Folk Song" or something ridiculous like that, with no name attributed. Mozart and Beethoven are known for their unique styles and having pushed the limits of music at that time. You must expand your musical ideas (get ideas by listening to lots of music!). This does not necessarily mean that your music must be more difficult, just unique.
This piece is simple, not like life (absolutely not like life), but simple, like what everyone wishes life would be like. I hate to get philosophical, but music isn't just ink on a page and pretty sounds! Example:
Life ≠

Life =
I do not say all this to degrade your work, but only to incite in you something that is more than just fluff and sensitivity. Perhaps those who will play the music won't understand, perhaps they will, but that's not the point.
By the way, I do understand you're new to composition, or relatively at least, and that you may not be terribly schooled in music theory and instrumentation.
If you really want to get better...just keep working!
Take care,
Evan