Error Handling In Stored Proc

I have a stored proc that loops through records using a cursor. If during the loop an error occurs i need to trap the error and write it to a log file.
Error handling needs to be placed in the update and insert sections and the error that occurs needs to get recorded along current row from the cursor.

Here is the code:
declare
@tier_id int,
@tier_desctext varchar(50),
@tier_shortdesc varchar(50),
@long_name varchar(50),
@short_name varchar(50),
@rec_count int

--Cursor for UES data
DECLARE cr_ues_tier INSENSITIVE CURSOR
FOR SELECT DISTINCT tier_id, tier_desctext, tier_shortdesc
FROM "dbsourcedayoldprod".ues.dbo.Tiers

OPEN cr_ues_tier

--Select cursor values into local variables
FETCH NEXT FROM cr_ues_tier INTO @tier_id, @tier_desctext, @tier_shortdesc
WHILE (@@FETCH_STATUS <> -1)
BEGIN

--Set Data Mart variables
SELECT @long_name = long_name, @short_name = short_name
FROM uesrpt..coverage_level
WHERE ues_tier_id = @tier_id

--Set the record counter
SET @rec_count = (select ues_tier_id from uesrpt..coverage_level where ues_tier_id = @tier_id)

--Are there exsisting records if so go to the update section
IF @rec_count <> 0

--Update Data Mart values if they have changed
BEGIN
IF @long_name <> @tier_desctext
OR (@long_name IS NULL AND @tier_desctext IS NOT NULL)
OR (@long_name IS NOT NULL AND @tier_desctext IS NULL)

OR @short_name <> @tier_shortdesc
OR (@short_name IS NULL AND @tier_shortdesc IS NOT NULL)
OR (@short_name IS NOT NULL AND @tier_shortdesc IS NULL)

UPDATE uesrpt..coverage_level
SET long_name = @tier_desctext,
short_name = @tier_shortdesc
WHERE ues_tier_id = @tier_id
END

--Rows don't exsist in the Data Mart - Insert new rows
ELSE
INSERT INTO uesrpt..coverage_level (ues_tier_id, long_name, short_name)
SELECT @tier_id, @tier_desctext, @tier_shortdesc

--Get next row from UES cursor
FETCH NEXT FROM cr_ues_tier INTO @tier_id, @tier_desctext, @tier_shortdesc
END

CLOSE cr_ues_tier
DEALLOCATE cr_ues_tier
GO

Any help is appreciated.
Thanks.