Tune your uke:

https://ukebuddy.com/ukulele-tuner

http://ukulelego.com/articles/tune-ukulele/

Excellent tutorials for beginners are available at:

Bernadette Teaches Music: https://www.youtube.com/playlist?list=PLJFa3EaocfZncpdhCRBCF302yIHnaRxOq

Cynthia Lin: https://youtu.be/A0mJxQbXWAc

Phil Doleman: https://www.learntheukulele.co.uk

Ukulele Mike Lynch:  http://www.youtube.com/user/MusicTeacher2010

How to read chord charts:

http://ukulelehunt.com/2008/03/19/how-to-read-ukulele-chord-charts/

https://ukuguides.com/how-to/how-to-read-ukulele-chord-diagrams/

https://www.youtube.com/watch?v=eGh7E8dJw8Y

Strumming patterns and techniques:

Strum Pattern Diagrams

http://ukulelego.com/tips/ukulele-strumming-patterns-for-beginners/

Some other good places to look for songs are:

http://ozbcoz.com/
http://www.scorpex.net/Uke/
http://nwfolk.com/uketabs.html
http://ukulelehunt.com/ (this is the most popular site for everything ukulele – info for new ukers, videos, chords, etc.)
http://www.chordie.com/
http://www.doctoruke.com/songs.html (he also has a beginner link with easy songs)

http://lewishamukulele.wordpress.com/songs-songbooks/

http://bettyloumusic.com/bettyloupop.htm

https://ukulelewednesdays.com/songbook/

https://ukutabs.com/