Checking that a cell contains 4letters then 7 numbers

Awesome, this looks like exactly what I was after!
Thanks so much!
I'm just having trouble switching it up to apply to a single cell (in a template that we constantly use)
I'm using excel 2013 - would this affect it any?

G7 is the cell in our manifest where we input the Can #s
(where would I be putting this formula in? I've only used '=' in a cell for a formula before, this is new to me sorry)

Thanks a ton! Got it to work - life saver!

*Updating the form some more*

My job uses a lot of C-cans which are labeled as 4 letters followed by 7 numbers, and contain different material inside them that is also numbered.
On the packing slips I generate for this cargo it is very important to not have any mistakes - so I had help making a macro to turn cells RED if they didn't contain the correct info ie."4 letters followed by 7 numbers". (See below for the Can# check)

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I'd like to do something similar for multiple other boxes. Some things to add are:
1) Cell C5 must contain the text "Shipment #" followed by 2 numbers [0-9]{2} example: Shipment # 02
2) Cell C7 must contain the text "Seal # UL-" followed by 7 numbers [0-9]{7} example: Seal # UL-1234567
3) Cell G5 must contain the date in format of 11.11.11
4) Cell G6 must contain 8 numbers followed by a "-" then 2 numbers example: 12341234-12

5) Then cells B18->B26, F18->26, G18->26, and G38 must contain at least 1 number.

I've tried tackling this on my own - for instance for #1, with stuff like:

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but I'm not so familiar with how these things work, or where I should be copy and pasting that code to. Ie. within the sub of the last macro? on a new one with the option explicit text again? etc.
(Attached a blank copy of the form I'm using)

Any help would be greatly appreciated!! Thanks in advance