what are the events recorded in the transaction log?
Every transaction in SQL Server is logged in someway or other depending on recovery model. fn_dblog and fn_dumpdblog both undocumented command would give you nice view what is present in transaction log but the result could be massive. What I do is I run whatever transaction I need to do within begin tran and commit/rollback and then only capture logs I need to using below query

BEGIN TRANSACTION TRANSACTION_NAME
SQL QUERY
COMMIT TRANSACTION OR ROLLBACK TRANSACTION

--Then use below query to filter out records related to the transaction

USE DATABASE_NAME
GO
SELECT
OPERATION,
Context,
[Transaction Name],
[AllocUnitId],
[Page ID],
Description,
[Lock Information]
FROM FN_DBLOG(NULL,NULL)
WHERE [Transaction ID] in
(
select [Transaction ID] from
fn_dblog(Null,Null)
where [Transaction Name]='TRANSACTION_NAME'
)


You can run 

SELECT * FROM FN_DBLOG(NULL,NULL)


To see all column names which fn_dblog would produce

Example: I would show what all things are logged when simple update command is fired

Begin tran T1

update [dbo].[IXBUILD] set C2='XXXXXX' where C1=1

Commit





Its has one row for begin tran one for commit and one regarding update operation. You can see LOP_BEGIN_XACT for beginning of transaction and COMMIT for commit of transaction.
LOP_MODIFY_ROW says a row was modified like we did in update statement.
LCK_Clustered_index is in picture because table had CI and row must have been exclusively locked for update
Then comes hexadecimal page ID which actually says what page had row which was modified
Then last column Includes the lock Information. The lock which was taken on HoBt 72057594041860096:ACQUIRE_LOCK_IX OBJECT: 8:613577224:0 ;ACQUIRE_LOCK_IX PAGE: 8:1:344 ;ACQUIRE_LOCK_X KEY: 8:72057594041860096 (8194443284a0)

Database ID=8 file number 1 and page 334. You would also see KEY value
There is also a log sequence number for every transaction and column Log Record Length which would tell you LSN and size of log record for particular operation


This was just a small demo. Remus Rusanu has explained how to read transaction log in details in This article please read it