Those sequences are too short to serve as an example, and there is no missing sequence in your example which is the whole point of the exercise.

Imagine you have the 3’ end of Contig A:

...ATCGACTAGCTAGCATCGATCGACTAGCTACG

And the 5’ end of Contig B:

GTACGATCGTAGCGGGCGCATTATCGG...

For this example, we will assume A is ‘left’ (5’) to B in the actual genome.

You would design primers which ‘aim’ at the gap between the 2 contigs.

             Contig A.                                  Contig B
—-ATCGACTAGCTAGCATCGATCGACTAGCTACG.............GTACGATCGTAGCGGGCGCATTATCGG—-
                                  ^           ^
                  Unknown sequence in the ‘join’ between contigs

Primers would be designed like so:

     Forward primer  TCGACTAGCTACG —->
—-ATCGACTAGCTAGCATCGATCGACTAGCTACG.............GTACGATCGTAGCGGGCGCATTATCGG—-
                                           <—- CGCTACGATCGTAC Reverse primer 
                                                             (reverse complemented)

PCR using those primers from a gDNA template would hopefully yield a fragment that you could subsequently sequence with Sanger sequencing.

I would advise you to search google for papers and figures with the query “gap closing by PCR” or similar.