Fill Series and Adding Time with SUM

[Minecrafter1005]

Hi. I'm doing a project where I add up a certain amount of times and show the amount of times next to it.
(Total Hours is meant to say Total Time (mins))

Like this. However, instead of adding the amount of time, it adds what time of day it would be. I need to change that (eg. 1:00:00 + 1:00:00 = 2:00:00).
The second issue, is that I want to be able to fill series with the sum. The equation is
=SUM(F3:F3)
=SUM(F3:F4)
=SUM(F3:F5)

and so on, but I don't know how to fill in the series properly. And whenever I try to do it I get the error message that says "Formula Omits Adjacent Cells".
If anyone can help with this, it'd be much appreciated! Thanks.

 

[davesexcel]

In G4 could you use
=f4+g3
then drag down

 

[Minecrafter1005]

In G4 could you use
=f4+g3
then drag down

Works perfectly for the automation! Thank you!

Now I just need to figure out how to add it up in 'amount of time' instead of 'time of day'

 

[Minecrafter1005]

Works perfectly for the automation! Thank you!

Now I just need to figure out how to add it up in 'amount of time' instead of 'time of day'

Fixed it, I had to go into Format Cells -> Custom -> hh:mm:ss

All good, thanks for the help.

 

[davesexcel]

I belive column G cells would require custom formatting
[h]:mm

edit:Oh, I see you found a solution