The United States Code (U.S.C.) contains the current federal statutes and is what you use for your federal statutory research.
Codification
Just like on the state level, newly enacted federal laws (called public laws) are codified by topic into a code. Remember from the discussion of Arizona Revised Statutes that codification is the process of taking legislative acts which create/amend statutes and arranging the statutes by topic into a statutory code. The purpose of codification is to put all the current statutes on the same topic together so it is easier to find the laws in effect about a specific topic.
Official Version
The official version is the print version published by the Government Printing Office (GPO). It is not annotated and the volumes are always several years out of date (the GPO is very slow to publish them) so it is not very good for research puposes. There is also an unofficial GPO version online.
Annotated Versions
Luckily, commercial publishers moved in to fulfill the need for and up to date and annotated version of the United States Code!
There are multiple unannotated out of date versions of the United States Code available for free online which you can find by Googling.
There is NOTHING new to learn about searching for federal statutes (United States Code (USC) sections). You search for federal statutes the exact same way you search for Arizona statutes!
Westlaw Example - United States Code Annotated (USCA)
You are interested in statutes about asylum!
What are the different ways to find relevant statutes?
Why is finding a relevant statute one stop research shopping if you are using an annotated code?
During your one stop research shopping, how would you find cases/decisions/guidance about gang threats, violence, etc...?