There are several ways to search through congressional documents on https://www.congress.gov/. Below you will find a brief description and link that can give you helpful information on learning search terms that can maximize your results.
This help site shows the various fields available to be searched, as well as examples that can be used in the main search box. These can be combined with operators such as AND, OR, NOT.
There are different codes for different statuses of the legislative process. These codes are numeric, and can enable you to find out what bills are waiting for the senate to review, for example.
Sometimes searching can be improved by knowing the preapproved subject terms a database uses. This link gives a long alphabetical list of subject terms that will make your search easier and fruitful.