Ok, I have a database where we want to tracking how long it takes us to do two different tasks but using the hh:nn:ss but not the actual time. For example, it took me 1 hour, two minutes and three seconds, needs to be notated in the field as 01:02:03 then I have a field that would take that field and the other field with the same format to give me a total.

For example, the second field is 01:00:43 (1 hour and 43 seconds) so I would get 02:02:46 = 2 hours, 2 minutes and 46 seconds. I thought I could use DateDiff Function but it won't work. Does anyone have any suggestions?

The second question that I have is since this database is in a work flow, each step has a Date Completed and Date Received so one process is completed the date received in the next process needs to be autofilled with the date completed information. does anyone have a suggestion?? Thank you. I am really trying to do everything that my new job is asking for. If it cannot be done, let me know so I can suggest another option.

Why? What's the expression (SQL or VBA) you used and what was returned (unexpected value or error)?

store the value as a date time value the date part will default to 01 Jan 1900, but that shoudln't matter.
after its stored as a datetime value then you can use the datetime functions such as datediff

but then again
there is no reason why you cannot store the datetime a process started and a datetime when the process finished

the process doesn't need to be autofilled as defacto when the proceeding process completes then its available for the next process which depending on the production may happen immediately afterwards or may happen at a time int he future.

For the first part of my question, I put in my it in DateDiff("hh:nn:ss",[Field1]+[Field2]+3 minutes).

You confuse the syntax of the DateDiff function with the syntax of the Format function and you mix both in the expression.

See: DateDiff Function - Access - Office.com
And: Format Function