Please post your desired output from your example.
Better yet is to show 2-3 examples and the desired output for each of them.

As far as I can tell there is only one string that is between a G(...)and 10+ more G's.
Update: shortened the very long string so it displays better.
Your question is not clear. Your code is not right.

Given the string: "GGCTTTCCGTTGTTGCTGGGTGTGGGGGGCGGGCGAGATTGGAAGAGCACA
+CGTCTGAACTCCAGTCACG".
"CCAATATCTCGTATGCCGTCTTCTGCTTGAAAAAAGGGGTGGGGGGGAGGGGGGGCGGGGGGGGGGGGG
+GGAGGGGGGGAG", please explain in english what you want to accomplish.
+ I have no idea what this means
[download]

"ACTCCAGTCACGCCAATATCTCGTAT"  "[ACTG]{0,10}"  " .+"  "(G)\1{9,}   ".+ "
or how that relates to 10 G's or more in a row.

Update:
is this what you want?

#!/usr/bin/perl
use strict;
use warnings;

while (my $line=<DATA>)
{ 
    chomp $line;
    my @array = $line =~ /(ACTCCAGTCACGCCAATATCTCGTAT)(.+?)(?:G{10,})/
+g;
    
    print join ("\n", @array),"\n";
    #prints "ACTCCAGTCACGCCAATATCTCGTAT"
    #       "GCCGTCTTCTGCTTGAAAAAAGGGGTGGGGGGGAGGGGGGGC" -> stuff befo
+re 10 or more G's

    
}

__DATA__
GGCTTTCCGTTGTTGCTGGGTGTGGGGGGCGGGCGAGATTGGAAGAGCACACGTCTGAACTCCAGTCACG
+CCAATATCTCGTATGCCGTCTTCTGCTTGAAAAAAGGGGTGGGGGGGAGGGGGGGCGGGGGGGGGGGGG
+GGAGGGGGGGAG
[download]