OK, if you believe you're a beginner and need to warm-up, here's a list of tasks to do using ruby before starting this book.
Strings
Print the following string \x52\x75\x62\x79\x46\x75 as it is, it should NOT be resolved to characters.
You have string RubyFu , convert this string to an array (each character is an element).
Arrays
You have the following array ["R", "u", "b", "y", "F", "u"] convert it to string RubyFu.
You have the following array ["1", "2", "3", "4"], calculate the sum of all elements.
Files and Folders
Find all files ending with .jpg or .pdf or .docx or .zip in your Downloads folder.
Create a folder called ruby-testfu and copy all found files (from the previous task) into it.
Network
Create a simple TCP server listening on port 3211. This server prints date and time.
Create a simple TCP client to connect to the previous server and print what the server sends.
A good list of References can be found under the Beginner section.
Challenge Yourself!
There are some awesome websites that push your programming skills via interactive challenges and I really encourage you to go through one or more of them.