The bill history is a list of all legislative actions on a bill, and the dates on which each action took place. Most commonly, one uses the History or Actions tab when looking up the bill on the Texas Legislature Online (TLO) or Legislative Reference Library of Texas (LRL) sites. It can be helpful to look up a bill's history on both the TLO and LRL sites as there are slight nuances in content. See below for more information about using bill history to research amendments and statements of legislative intent.
While the bill file (discussed in step 3) contains some information about amendments, it can be helpful to look at the bill history in particular to see what, if any, type of amendments were passed, and when (in committee versus on the floor).
A house or senate committee can report out a bill various ways: favorably without amendments, report unfavorably, report favorably as amended, or report favorably as substituted (a "committee substitute"). TLO's/LRL's Actions tab entries will note, for example, "Committee substitute considered in committee" or "Reported favorably as substituted." A committee report will note if a bill is a substitute, and will add a "CS" to the bill number. (Ex: HB 20 would become CSHB 20.) In the House or Senate Journals, a bill is noted as CS until it passes as engrossed to the other house. LRL provides more information on how to search a bill's amendments.
Every once in a while, statements of legislative intent will be recorded in the House and the Senate Journals. More recent sessions will include references to statements of legislative intent in the list of actions on a bill, or bill history. If so, double check the House and Senate Journals directly to verify the statement; TLO may provide page number and link directly to relevant portion. (Prior to the 75th Legislature in 1997, statements of intent were inconsistently noted in the actions.)
Since the Sunset Advisory Commission legislation that you are researching is from the 80th Legislature, the bill history can be found on the Bill Lookup section of the Texas Legislature Online website in the same way that you found the bill file.
Here is a section of the bill history for House Bill 3249, 80th Legislature:
The H, S, and E that appear on the far left side indicate whether the action took place in the House, Senate, or Executive branch. In the column furthest to the right, the numbers indicate which page of the appropriate Journal (House or Senate) include bill entries. You will also want to make note of the dates of legislative discussion; you will need this to obtain audio tapes, if necessary.