Lifeprint.com Is a great source for beginners in Sign Language. They even have wallpapers you can put on your phone to practice your letter or numbers.
Colors are easy to learn. There is a fast paced youtube video linked below that you can pause as needed to learn the signs.
The Alphabet can be tricky to learn but not to worry because it is easy to memorize. This is a Youtube link to someone who will help you by making it slow and repetitive and easy to learn.
Additional signs you can be learning and the links to them below.