Notice the little 3's under the notes.
these are triplets.
I think what they are going for here is a swung eight note feel, but it is not notated that way and in my opinion is much harder to read.
in the 3rd image above replace the quarter note with the 3 under it (the D, if this treble clef) with 2 eighth notes with 3's. and play it like a triplet. now, tie the first two notes together and that is what you have.
In youcisian, go to practice mode, and in the tempo slider menu, select mute song, and play for me. will help if you also turn the metronome on. this will let you hear how it sounds.
As far as free music, if you are just practicing sight reading, or reading in general, try the library. My library has a small (too small sadly) section of song books.
Also if you are affiliated with a church see if you can borrow a book of hymns.
Used book stores or even good will may have a selection of cheap sheet music people have donated.