How to read song sheets?

Dear all,

I have started playing ukulele a couple of months ago and I have only played with (simple) tabs so far.
Could someone explain me how to read song sheets? I just cannot understand them...There is no information on strumming pattern, tempo...Well, I'm lost!
Do we need to know the songs (and tempo) to be able to play them?

Below are examples of songs I would love to play...
Mama mia (Abba) : http://www.scorpex.net/uke/Mamma_mia%20_in_%20C.pdf

Bang Bang: http://www.ukulelesongs.com/uke/ukulele_chords/music/tabs/Sonny_Bono/Bang_Bang.php

Thank you!

You need enough familiarity with the melody and the "feel" of the song to be able to work your way through these. After you've played a variety of songs you tend to develop a "vocabulary" of strumming rhythms, and start to intuitively figure out patterns that fit the new songs you're learning.

The leap you have to make is from having somebody dictate the pattern to you, to using your ears and the technique you've acquired to start coming up with strumming patterns on your own. Be patient - it comes with practice, and with expanding your familiarity with a variety of song styles and tempos.

It's also fun to experiment and come up with your own style for the song - such as turning a hard rocker into a gentle ballad, etc. The ukulele can really change the character of a song, with some delightful results. Do some youtube surfing on "ukulele cover" and you'll hear a wide variety of song approaches!